2000 Sonata, Automatic, 4 cylinder, 107,000km.
So about a month ago my Check Engine light came on again. This time I
took it to a Hyundai dealer/service center. It was the same computer
code again, P0171 (mixture too lean), that the other shop (a few months
earlier) had tried to fix by, essentially, giving me a tune up. This
time the Hyundai service center told me it was a leak in a front exhaust
pipe dealing with the emissions system. They fixed the exhaust under
warranty, which was a pleasant surprise because the car has over
100,000km on it.
But last week the light came on again. This time they said it was the
air flow sensor and they charged me over $900.00 CAD (incl labor and
tax) to install a new one.
It seems to me that this code can mean almost anything, and that these
guys are just going to keep telling me I need to do more stuff and
charge me more money every time the damn light comes on.
Then their head mechanic, who they've built up as being some kind of a
"master mechanic", tells me that my timing belt needs to be changed. I
inform him that I already had it changed in Feb. 05 @ 73000km. He then
says that, in that case, they didn't do it right and that "the
counterbalance shafts, on the exhaust side, aren't timed properly". He
says he can tell this because he feels a vibration in the engine at
3000RPM. To demonstrate this vibration, we sat in Park and he revved the
engine up to 3000RPM. It sounds totally normal to me. Sure, the car
vibrates at 3000RPM a bit more than it does at 2000RPM and a bit less
than it does at 4000RPM. Isn't that normal?
So, now he wants me to go back to the guy who changed my timing belt and
try to convince him that something's wrong enough for him to open the
thing up and re-set the timing on the the counterbalance shafts for
free. By this work was only warranted for a year and that time has
passed already. Plus, I don't know how I would convince him that there's
anything wrong. If the original guy (who also owns a Hyundai dealership
btw and claimed to know these cars inside/out) won't do the work, then
the "master" says it'll cost me about $400.00 labour to do it at his
shop (assuming that the parts are not malfunctioning and need to be
What do you think?
Are they taking me to the cleaner's?
Except for the Check Engine light this car has been running great lately.
The "master" says that even with the timing belt's mistiming, the car is
safe to drive. But he says that after 20000km there might be serious
problems. He mentioned a bearing possibly going bad because of this.
Based on what I've said here, do you think I need to have the
counterbalance shafts timed properly too?
Thanks for any info. You're always really helpful, and I appreciate it.
When diagnosing a car based on a trouble code, it's important to keep in
mind what that specific trouble code means. In your case, the trouble
code P0171 doesn't point to any specific component but rather that the
amount of adjustment to the fuel being delivered doesn't fit within the
parameters of what the PCM considers normal operation.
Your PCM measures how much fuel it delivers by how long it keeps each
injector open. The code P0171 specifically means that considering the air
flow, throttle position, and other values, the PCM believes that it must
keep the injectors open longer than reasonable to provide the proper air
fuel mixture as measured by the air flow sensor.
The actual problems typically fall into one of several groups:
1. Low fuel pressure
2. Faulty air flow sensor readings, which would include air entering the
engine which wasn't measured by the sensor, such as a broken air intake
hose or a vacuum leak.
3. Skewed oxygen sensor readings.
First off, a tune up will not fix a P0171 issue. Nothing relating to fuel
mixture or its measurement will change by doing a tune up. I could see a
remote possibility of an exhaust leak being the issue. I've seen very
small exhaust leaks cause oxygen sensor trouble codes. Because of the
relationship between the oxygen sensor and P0171, I can fathom that this
is a possible scenario that I've never encountered as yet.
The air flow sensor is likely to be the real issue, however. Of all the
cars I've seen with the P0171 code, nearly all have been broken or split
vacuum hoses (of significant size) or defective air flow sensors. Hyundai
has had some problems with oxygen sensors, but the failures (on Hyundai
sensors) tend to be with the oxygen sensor not cycling properly rather
than the skewing of the values that would be necessary to set P0171. And
again, low fuel pressure is another possibility, but this is very rare.
In most cases, the driver experiences a severe hesitation on acceleration
long before the computer can detect a P0171 issue.
In regard to the balance shaft issue, the technician is probably correct.
Most technicians wouldn't know what the balance shaft vibration felt like
to point it out; nor would they have any alarm upon feeling the vibration.
The potential causes are:
1. One of the balance shafts is not timed properly, or
2. The balance shaft belt has broken.
If the shop that serviced the vehicle previously replaced the balance
shaft belt along with the timing belt, then there's little to be alarmed
about. The largest problem is likely to be the vibration itself. If the
balance shaft belt wasn't replaced, there's plenty to be alarmed about.
If the balance shaft belt breaks, it can get caught in the timing belt,
which in turn can make the timing belt jump time and cause engine damage.
We had a situation at the dealer where I'm employed when a less-experienced
technician took a car with a broken balance shaft belt on a test drive
looking to find the cause of the customer's "noise." The balance shaft
belt came loose, got into the timing belt, and we ended up needing to
replace the cylinder head and valves.
Here are my opinions based on what you've said:
1. This repair facility attempted to cure a P0171 issue by doing a
tune-up. This indicates that the person who checked your car didn't
understand what the code meant and what could cause it, or didn't care and
wanted to do a tune up.
2. The master to whom you spoke seems knowledgeable. If he wasn't the
one who worked on your car when the tune up was done, you should maybe
consider having him do all further diagnostic work on your car. Of
course, if he's the one that recommended the tune-up, scratch that.
3. Check your receipt from the other shop to see if they replaced the
balance shaft belt along with the timing belt. If not, have them both
replaced, and by someone other than the shop that originally did this
work. Any shop that would replace the timing belt without replacing the
balance shaft belt is not looking out for the best interests of their
4. If the other shop did replace the balance shaft belt, ask them if
they'd be willing to recheck their work. Even though you're outside the
warranty period, they may be willing to do this. The front (exhaust side)
balance shaft is particularly easy to mistime because the sprocket doesn't
turn in a 1:1 ratio with the balance shaft. Simply lining up the marks
doesn't guarantee it's timed properly. For what it's worth, if I find a
problem with my work (i.e. something that I personally did wrong) that
caused a problem, I'm willing to fix it regardless of the warranty period.
Thanks for your extremely detailed, well thought-out, response.
The shop that did the timing belt work did do the balance shaft belt
too. Or at least that's what it says on my receipt. They charged me for
the labor and the part. So I guess I'll do what you've suggested and ask
them if they're willing to check their work.
But as you said, "Most technicians wouldn't know what the balance shaft
vibration felt like to point it out". I hope that the technician at the
original shop can feel the vibration too. Otherwise they probably won't
believe that there's anything worth checking.
I'll let you know.
Regarding the P0171 code:
It's been 3 or 4 days since they changed the air flow sensor. I've
driven about 300km (75km both ways, twice, on two separate days) on the
highway. So far, no "Check Engine" light. I'll keep my fingers crossed.
I hesitate to go to the Hyundai dealership for my auto service because
they tend to be a little bit more expensive than other service centers.
But maybe I should just stick with them. They happen to be located right
down the street from where I live too.
Yesterday, the front passenger-side brakes started to make a grinding
noise. Now I have to decide if I'm going to take it to a brake shop or
back to the Hyundai dealership.
This f...... car keeps soaking up all me money.
I took it to the Hyundai dealership for the brakes.
They charged me $560.00 CAD to replace the front pads and rotors.
They say the rear brakes will need to be replaced in another 12k-16k km.
The crap I've had to pay for since I bought this car in late 2004 (new
rad, new windshield washer pump, timing belt(s), power steering drive
belt/pulley, and now the brakes) hardly seems like normal wear and tear
on a 6.5 year old car.
I thought I had it bad in '04 when my 87 Buick Century had to get a new
gas tank. I don't think that car, even in '04, was costing me as much
per year in repairs as this Sonata is. I hope this is just a 100,000km
hump I have to get over and that the next few years won't cost me so much.
And I thought that with brakes, you drive until you hear a grinding
sound, and then you get your pads changed for around $200.00.
These brakes have been squealing a bit, off and on, in various weather
conditions, since I bought this car. But every service center I've taken
it to has told me that that noise was normal. Yesterday they start
grinding, rather than squealing, so I take it in today, as soon as I
could. And BAM, 560 bucks. Geez.
This thing with the timing belt balance shafts better work out so that
the guy who did the work fixes it for free, or I won't have any spare
cash for months.
Except for the occasional squealing I mentioned earlier the brakes have
given me no sign of anything being wrong.
I don't remember having to spend over $1000.00 on brakes every 6 or 7
years on a new car. (For front and rear... Evidently in 12,000 to 16,000
km I'll need the rear brakes done too.)
Granted, I'm more than a little green when it comes to automotive stuff,
but I'm not that green.
On the Hyundai service center's wall they have "Brake Service $79.95 -
front" and "Brake Service $79.95 - rear" proudly displayed.
How my brakes got to the point of needing $560.00 worth of work is
beyond me, especially since I've always brought up the brakes every time
I've had the car serviced for 2 1/2 years, and *everybody* told me they
Because by the time you hear a "grinding noise" it's already too late,
as the metal-to-metal contact is already in the process of destroying
your rotors. (The exception would be GM models that have a noisemaker
designed to make such a sound in a non-destructive manner. These use a
pad-mounted metal "finger" that contacts the edge of the rotor when the
brake linings get low. Most makes and models of cars do *not* have this
I would not consider it unusal for a 6.5 year old car to need new brake
pads. The reason for needing the rotors is that the pads were permitted
to wear down too much before replacement.
The price you paid for the job seems a little high. Rotors and pads are
pretty cheap, I installed a set on our 1985 AMC Eagle recently, I think
the pads were about $25 and the rotors about $30 each (US$), and they
were pretty simple to install. However I do most of my own work,
except on the wife's 2006 Sonata which gets dealer service and has
needed no repairs yet, so I don't know what the going price is for that
kind of repair job in a shop.
To reiterate, on most cars the brakes will not give you any indication
that the pads are worn down until it is too late. They need periodic
inspection to prevent the kind of problem you encountered.
Your statement. Do you really think you just drive until the noise gets
loud and grinding? When the pads wear beyond their limit, the metal
portion starts to rub against the rotors and ruins them. That is why you
inspect them on occasion to see if they are at the replacement point. Some
pads to have wear indicators that make a noise so you know something is
amiss, but that is not very reliable.
Cauht at the right time, it may be that all you needed is pads. Left to go
to long, more work is needed. At 6 or 7 years, calipers often need to be
rebuilt or replaced. Anything mechanical will eventually wear out and/or
No, they just gradually wear. Every time you hit the brakes, a tiny bit of
the pad wears away. It is designed to do that on every car made.
And if done at the right time, it may be the $79 service that is the only
thing needed. Also, the miles (or kilometers) drive mean nothing to brake
wear. It is the number and type of stops. I can drive my 26 mile route to
work and hit the brakes as little as four times. When I lived in a larger
city, I'd use the brakes probably 100 or more times in that distance. Some
streets have a stop sign every block, or about 10 stops per mile.
They probably were fine for the first 2 to 2 1/4 years. It is the last
portion that did you in.
Of course, I did not see the brakes and rotors, nor did I see what was done.
The price may or may not have been fair. It still goes back to getting them
serviced at the right time. Yes, some pads will make a squealing sound, but
once you hear grinding, it is already too late.
You also mention you had a Buick that seems to be far less troublesome.
That is not my situation. The brakes on my Regal were are real expensive
PITA (traded that in for my Sonata) and I just put new pads and rotors and a
wheel bearing on my LeSabre. The rotors were warped. Second set on the
LeSabre in 120,000 miles. Price was in the neighborhood you paid, IIRC. I
had a few other th ings done and it was an $850 bill total.
I'd also consider trying a different shop. If not warranty related, dealers
tend to be higher priced that the independents and more willing to change
parts, needed or not. There are good and bad mechanics and good and bad
shops of all types. Find a good one and stick with it.
Granted, $1000 is quite high, but that's why it pays to do your own brake
work. It's not complicated and the price of brake work, relative to the
cost if you do it yourself has always been in orbit. That said though, one
can hardly call a car that is 6 or 7 years old, "new". The mileage is low,
but it's not all about mileage. It's more about the number of stops you
make in your normal driving. Either way - look around a bit and you can
certainly find prices for a complete brake job that are far more reasonable
To be fair, if you drive a car until the brakes make a grinding noise, then
you can't expect anything less than what you've experienced. That grinding
is metal to metal destruction at work. I have a hard time believing that a
number of mechanics looked at brakes that an owner complained about,
observed worn down pads and told you not to worry. That's just not how
Brakes give plenty of indication that they are approaching the point of
being worn out. It only takes an occasional look to see what the condition
of the pads is. All brake pads start out at about 3/8" thick, and all brake
pads are mounted on a hunk of steel that is easily distinguished from the
pad. It's as easy to see worn pads as it is to check the amount of gas in
your tank by looking at your gas gauge. No mechanic would look at a set of
pads with 1/8" of life left and tell you all is well. Equally, it would
take some amount of driving to wear down that remaining 1/8". Certainly
plenty enough time to schedule the car in for service before you ate up the
First off, stop taking your car to the dealer for generic work like brakes.
Save you dealer $$ for work specific to the Hyundai, that's where they
excel. Anybody can do a brake job. Second, read the fine print under signs
like "$200 30,000 mile service". Other than a oil change the only other
verb you will find there is Inspect. Pretty expensive oil change!
"Joey Goldstein" < email@example.com> wrote in message
P0171 means that the ECM, using the values it reads from the oxygen sensor,
air flow sensor, throttle position sensor, and maybe a few other lesser
players, needs to hold the injectors open significantly longer than it
believes should be necessary to achieve the proper mixture. Once this
code comes up, it's up to the technician to figure out why. The problems
fall into a few categories:
1. Fuel metering issues, including low fuel pressure and clogged or
2. Oxygen sensor readings skewed low.
3. More air entering the engine than is measured, either due to leakage
or faulty air flow sensor.
On Hyundais, category 3 is by far the most common occurrence. On some
other makes, category 2 is also common.
First, I'll say that I'm not surprised that the tune-up didn't solve your
issue. If you look at the category list above, you'll see that nothing in
a tune-up addresses any of the items in any of the categories.
I'm also not surprised that the exhaust pipe didn't solve your issue. But
I'd have probably done that first as well. First, it was free. Second,
it's easily verifiable as a failure. And third, it's possible that the
oxygen sensor values would be skewed by a leaking exhaust.
The air flow sensor has probably solved the issue. The two most frequent
thing's I've seen for P0171 are faulty air flow sensors and broken or
split vacuum hoses of significant size.
As for the balance shaft belt issue, the technician is probably correct.
Few technicians would be able to identify a balace shaft belt vibration.
Most technicians would not notice the vibration at all unless they drove
the vehicle a significant distance. And even then, they wouldn't be
likely to identify what it was and recommend a repair.
The first thing to do is check your receipt from the other shop to see
whether the balance shaft belt was replaced when the timing belt was done.
If not, do not hesitate to replace the timing and balance shaft belts, and
never return to the shop that replaced the timing belt. If the balance
shaft belt breaks, it can come loose and get into the timing belt, causing
the main belt to jump time and damage the engine. Any shop that wouldn't
replace the balance shaft belt when replacing the timing belt is not have
concerned at all with the customer's interests.
If the balance shaft belt was indeed replaced, then it's likely that the
dealer technician was correct. The exhaust side balance shaft is tricky
to time properly. The oil pump/front balance shaft sprocket turns in a
2:3 ratio with the balance shaft, so lining up the marks isn't sufficient
to be sure the balance shaft is properly timed. It's doubtful that any
significant damage would occur if this were the case, but additional
fatigue from the vibration is a possibility.
In regard to the current shop, you need to ask a few questions. Why did
they recommend a tune-up for a P0171 code? If it was simply a matter of
having someone unknowledgeable working on the car, requesting the mechanic
who told you about the timing belt may resolve that issue. Hopefully he
wasn't the one who recommended the tune-up. The important thing to
determine is whether you were being sold a tune up because of technician
ignorance or because a knowledgeable technician simply wanted to sell a
tune up. In my experience, most repair issues result from a lack of
knowledge on the part of the technician, not any attempt to deceive or be
I'm not really sure why you responded to this a 2nd time. But I'll try
to fill in the blanks below.
Well it was not presented to me as a step along the way of fixing
things. It was presented to me as the fix itself. Maybe I misunderstood
what they were telling me at the time. But I was pretty peeved when that
Check Engine light came back on again. Sure the exhaust pipe fix was
free, but I have to keep going back to the shop and doing without my
car. It's a drag. I just wanted the thing fixed. And now they're into me
for over $900.00 on this. It better be fixed.
I hope so. Because if that light comes back on, after paying these guys
over $900.00 to fix it, I'm going blow my top.
This guy didn't drive it at all. He revved it up while the car was in
Park, on the lot.
When he first approached me about this, he assumed that the timing belt
had not been changed. It was only after informing him that the timing
belt and balance shaft belts had indeed been changed, in Feb. '05, that
he said that it was a timing problem of the balance shafts.
He tried to demonstrate the vibrations me too (in the parking lot), but
I didn't feel any *unusual* vibrations. Sure it vibrates more at 3000rpm
than it does at 2000rpm. And it vibrates even more at 4000rpm.
Been there done that. They did replace the balance shaft belts too.
Well, right now, the car is back with the guy who did the timing belt
work in '05. He's graciously offered to look into it for me. But he
thinks the dealership technician is full of shit. Keep in mind that this
guy, the guy who's shop did the timing belt, also owns another Hyundai
dealership. The guys who work for him should know these cars pretty
well. At the time, he assured me that they did. I'll be getting the car
back tomorrow. If he says that there's nothing wrong with it, or that he
refuses to do anything about it, then I have to decide whether I'm going
to believe the current dealership tech and give him some more money to
fix it, or take my chances and just let it go.
The dealership tech said that it was safe to drive for now but that he
couldn't vouch for things after another 20,000km.
They're not the "current chop". They're one of 3 shops that were
involved in all of this. They're an unaffiliated shop that just happens
to be nearby to where I live. I just moved here in December '03. I used
them for a couple of oil changes. And then when I had a power steering
drive belt problem I went to them too. The drive belt thing dragged on
and on too. They changed the belt, then it came off again a few weeks
later. 3 belts later, they replaced one of the pulleys too. It's been
fine for several months now. But it always seemed a bit noisier under
the hood to me since they changed the pulley.
When the Check Engine light first came on I went to them again. They
said they couldn't find the code with their software and that they
didn't know how to fix it. They told me to go to the Hyundai dealer,
also right near my house. But they reset the light and when I went to
the Hyundai shop they said they couldn't do anything for me if the light
wasn't on. At that time I didn't know the code number.
So, the light stayed off for a while, I forget how long. It came back on
right about the time I needed an oil change. I took it to the
non-Hyundai shop for the oil change and told them that the light was
back on. That's when they told me that they wanted to do the tune-up
stuff (spark plugs and air filter, etc.) and that that should fix the
Check Engine thing.
So I was peeved at them when the frigging light came back on 3 or 4
weeks later. It's like they were just trying stuff without having a clue
what was going on. I gave them a piece of my mind too (the guy swore up
and down how he had been doing me favors...maybe I needed a tune-up
anyways?), and then I went over to the Hyundai dealer.
The shop that did the timing belt work, in '05, is near where I used to
live. I'd been going to these guys for over 10 years and had learned to
trust them as much as any auto service shop can be trusted. When I first
moved into my new house I kept going back there, but it got to be too
much of a hassle. I think that the Sonata timing belt work, back in Feb
'05, was the last time I went to that shop, until today, when I asked
him to check their work.
I'll let you know what he says tomorrow.
OK. This keeps getting more twisted.
They say that the Hyundai guy was wrong. It wasn't a "vibration". It was
a "flapping". They took it apart (3 hours labor) and said that the cause
of the "flapping" was a roller than needed lubrication. Since they say
that, back in Feb. '05, this roller appeared to be fine, they don't
consider this to be their fault, and they charged me just under $300.00
for the work.
I thought I had been clear with the owner of the shop that all I wanted
them to do was to see if they felt the "vibration" too and if so to
check their work, and that it was understood that this was under
warranty (even though the actual warranty had expired).
Assuming that this is all behind me now I may have saved $100.00,
because the Hyundai guy was going to charge me $400.00 to take it apart
and correct what he said was causing the "vibration", what he said was,
"faulty timing of the counterbalance shafts".
So, hyundaitech, what do you think?
Would a roller that needs lubrication have cause the "vibration" that
the Hyundai guy said he was feeling at 3000rpm?
To tell you the truth...Now I think that *I* might be hearing/feeling a
vibration at 3000rpm! Other than all this bullshit, the car seems to be
running really well.
And the plot sickens yet again...
The guy (let's call him Tom) who just did the work (i.e. lubricated the
roller...for $300.00) just talked to the Hyundai guy (let's call him Peter).
Now Tom wants me to bring the car back to him so that he can check out
something that Peter just explained to him. I can't get there till
Friday. These guys are gonna drive me nuts.
To be continued...
Meantime. . . . . . Should the roller have been lubricated or replaced?
Given the $300 cost to get to the roller, I'd want some assurance it won't
come back in another few thousand miles. If the bearing is damaged, it will
Now would be a good time to run out and get two big containers of KY Jelly
and give one to each of the two guys you are currently dealing with. It
may save you some pain in the future :-)
On a somewhat similar note, my Mother owns a Subaru Forrester. Her brakes
were in need of front pads. She didn't want to "burden" me with the job
because of my kids, so she took it to the dealer. I marked all of the
parts she had before she brought the car to them and took pictures. After
the $700 reaming she got, I showed her all of the marks I made and pictures
I took to prove to her that all they did was replace the pads. It took an
entire year of B.S., but she just got a $5000 judgement from the court, the
maximum they could give her in small claims court. But the biggest
satisfaction she got was that Subaru just pulled the franchise from the
dealer. This was not their first complaint :-)
What does that have to do with you, Joey? Not much. I just hope it made
you feel good for a minute. Honestly, I hope you make out well from here,
but there isn't much I can do for you.
Sorry, Joey, I was just trying to add a little levity to your situation,
because I know it isn't funny when it is happening. If it helps any, my
Mom is Sicilian, and has a ton of cousins and Uncles that could help you
out as a last resort.
Hope that at least made you chuckle.
I must be jinxed, or somebody's put a curse on me, or both.
So I get my car back this afternoon (as detailed earlier in this thread)
and take my Mom to her dental appointment.
After we're done, around 4:30 pm, I go buy some gas to be ready for my
1 hour commute tomorrow morning. While I'm there, I decide to check my
tire pressure. All 4 tires are just at 32 psi, which is how I usually
set them. This is a bit surprising to me because my front passenger tire
sometimes seems to have a slow leak and is often down a few psi every
once in a while. The front tires are around 2 years old, btw. The last
time I put air in was about 2 weeks ago. Maybe, I think to myself, one
of the service shops I've been going to topped off the tire pressure for
me, or maybe it's just not leaking anymore.
I drive home. This gas station is 2 blocks away from my house btw.
At about 7:00 pm I decide to go out and do some grocery shopping at a
local mall about 5 minutes from my house. My car sounded a bit weird
getting out of my small driveway. Then about 3 or 4 houses down the
street I realize I have a f...... flat tire. The right hand passenger
side tire. I back it up and back into my driveway, cursing all the
My first thought is that one of the little tire valve extensions I use
on my tires got stuck after I checked the tire pressure. I usually leave
them on when I check the tires. It just turned winter-y here in Toronto
within the last few days btw. Maybe it got clogged with ice? I examine
it and it's quite rusty and the travel of its 'nipple' is quite rough.
But I'm not sure, because this isn't supposed to happen, or so I think
to myself. Maybe I ran over a nail in the 2 blocks it takes to get from
that gas station to my house?
I call the auto club (CAA...it's like the AAA). A truck comes by within
20 minutes, which is nice. He fills my tire. It stays filled for the few
minutes he's there, disproving the theory that I had a fast leak due to
a puncture. Remember, it took less than 3 hours for this tire to go from
full pressure to completely flat. He tells me to go get it checked anyway.
There's a service center that stays open till 9:00 pm and it happens to
be at the same mall where I had wanted to go grocery shopping. I decide
to go there and have them check out the tire, even though I'm convinced
that it had to be the faulty valve extension. Their guy says all he
found was a slow leak around the rim. He reseals the rim and cleans it
up a bit. While I'm there, 3 guys at this shop tell me that my valve
extension wouldn't have caused the tire to go flat like that.
I get the car back and there's still time to go grocery shopping, so I
do. I get back in the car and start to drive home. Half way home, my rpm
indicator, on the dash, stops working.
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