Oxygen Sensor On Dodge Durango

I have a 2000 Dodge Durango that is getting about 7 MPG. The check engine light is on. When I check the code it is 0171. I have had it
at the local Dodge dealer on and off for the past 9 months. They have done the following: Replaced both oxygen sensors 3 times.. Replaced the Cat Converter 2 times.. Check all the electrical wiring Check the fuel flow Replaced the spark plugs Etc....
It has a 4.7L engine with 150k miles. After spending about $2,000 dollars the dealer said they couldn't figure out what was wrong, just keep driving it until it dies......
Before the problem started I was getting about 16 MPG.
They have hooked the computer up to it and keep telling me that everything is ok, but the check engine lite will come on with 50 miles after leaving the shop.
Has anyone seen a similar problem? Any ideas what I can do to troubleshoot the problem other than keep driving it until it dies?
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Maybe it is time to stop donating money to the dealership, and try to find an expert mechanic somewhere.
Sounds like they have been throwing parts at it, hoping something will work.
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snipped-for-privacy@nospam.nix wrote:

The sensors and converter went bad for a reason. Replacing them treated the symptom but not the cause. Since the cause was not corrected, history repeated itself.
Various substances can "poison" oxygen sensors and catalytic converters.
Anti-freeze. Does the engine lose coolant? No external leak found? In that case the coolant is going out the tailpipe.
RTV adhesive. Was some repair done on the engine using RTV? It is a versatile adhesive but causes harm to sensors and converters.
Motor oil. Does the engine burn a lot of oil? If so, it may be depositing gunk and ash on the sensors and converter.
Leaded fuel. Not too likely. I don't think it is sold any more.
Have you been using one of those Miracle In A Can fuel additives? If so, that could be to blame.
Daniel B. Martin
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No anti freeze leak
No RTV adhesive that I know of
I may loose 1/2 a quart over 5000 miles, not excessive
No fuel additives
The dealership may have just replaced the parts even if they were not bad.
It looks like something in the engine is saying that it is lean, add fuel.
Is it possible that there is some sort of ground strap loose?
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macdad wrote:

You have convincing evidence that your oxygen sensors and catalytic converter are not being "poisoned."
I don't suspect that you have a loose or missing ground strap. However, it cannot possibly hurt for you to add a ground strap from the engine to the body and from the body to the battery.
There are cases where a lazy or unqualified technician reads a Diagnostic Trouble Code which points to an oxygen sensor and so he replaces the sensor without much thought. In so doing, he jiggles the wiring related to that sensor. As an unintended consequence, a faulty connector or a broken wire is "fixed" for a while, but the problem comes back.
When the Engine Control Module ("the computer") sets a DTC pointing to a particular sensor, it is saying "the signal from that sensor looks wrong." The ECM cannot distinguish between a bad sensor and a bad wire carrying that signal. A technician who is doing a thorough job troubleshooting a repeated failure should disconnect the electrical connector at the ECM and connect an ohmmeter to the sensor pin at the ECM end and to the sensor pin at the sensor end. The reading should be zero ohms. Then he will twist and flex the wire, and the harness through which the wire runs, to see if the reading remains zero ohms, as it should.
I've read of cases where a wire was spliced to effect a repair. The splice was good for a year, maybe for two, and then the trouble began. Have you ever had electrical repairs done to your truck? Has it ever sustained collision damage which required wiring repairs?
Daniel B. Martin
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In article

That would be the bank 1 oxygen sensor. The next logical step would be to determine the reason that bank 1 is running lean.

Doubtful. The oxygen sensors do not reference against ground potential. Any other sensors with a bad ground would result in the PCM seeing higher than normal voltage, MAP , TPS and coolant temperature equate to richer running when the sensor voltage goes higher, your situation is the opposite.
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If this were me I'd be in small claims asking for my money back, " drive it till it dies" after taking your $2500, unbelievable.
wrote:

-
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You don't know that they were bad, Daniel. The OP just said they replaced them.
But I fully agree...the mechanics have not done a thorough diagnostic job, and have thrown parts at this car.
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snipped-for-privacy@nospam.nix wrote:

You are right. Perhaps I was giving the dealership people more credit than they deserve. In any event, they had an opportunity to satisfy this customer and they failed. It's time to give somebody else a chance.
Daniel B. Martin
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wrote:

Failed is a far cry from what happened. The OP has paid $2000 for bad advice and no change from his original situation.
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macdad wrote:

What peak-peak voltage did the original pair of sensors put out? What did the 1st replacement pair put out? The 2nd? The 3rd? The only way so many O2 sensors could have gone bad in such a short time was by gross contamination, and I seriously doubt that happened.

Did they melt (back pressure over 2-3 PSI at 2,000-3,000 RPM) or become contaminated?

No they didn't. There's just too much wiring.

What did they meausre? And what about the fuel pressure?

Act of deperation.
You may want to try a bottle of Chevorn Techron in the gas tank, but don't overdo it, and don't let a garage flush the injectors since that often damages injectors for good.

Any decent mechanic would have hooked up his computer to the vehicle's to read the vital signs for abnormalities while the engine was running and probably pinpointed the problem in 10 minutes.
Try Chrysler-specific web sites, like www.dodgetrucks.org, www.dodgetalk.com, or www.dodgeforums.com. Go to a library and find a factory or Mitchell manual because Haynes, Chilton, and Motor aren't nearly as good for fuel problems. Get a digital volt-ohm meter (cheap one is fine, but digital is important, and frequency measurement or at least a fast-acting bar graph can be useful) and perform the component tests. If you buy an OBDII reader, forget about the cheap ones that simply display codes; you want one that can display all the sensor and actuator readings in real time.
Do a credit card chargeback in writing. The 60-day rule doesn't always apply, especially if you complained before paying (eliminates time limit), and Visa, MC, Discover, and Amex have their own rules that extend the federal 60-day limit to at least a year. If your dealer is AAA approved, complain to AAA and have them arbitrate (AAA arbitration is binding on the garage, not you). Also file complaints at www.bbb.org and your attorney general's consumer division.
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macdad wrote:

Hie thee to a better shop, hopefully with documentation of the dealership's "resolution" to the problem. I can't believe you've put up with such suck for this long.
nate
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Have they bothered to do simple things like a compression check? Have they made sure the ignition and valve timing is correct? Any chance the transmission is slipping?
It is sad to see how dealership shops have turned into scam centers. My SO has a Plymouth van that turned on the check engine light. After changing the plugs and wires a couple of times, the dealership suggested that the only fix was a replacement engine (2K+ dollars). Fortunately an independent mechanic diagnosised the problem as a burned exhaust valve. Still not cheap to fix (over $600), but certainly a lot better than $2K. My sister just got ripped off by a Ford dealership today. The car had a sticky IAC valve. The valve costs less than $70 and can be replaced in 15 minutes by an inexperienced mechanic. Her bill was over $500. In addition to the IAC,which she needed, they also charged her or a fuel filter (not a bad idea) and an extreme fuel system cleaning ($160) - a real rip off.
Ed

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I have owned the Durango since it was new. It was never in an accident and the only wiring issue I have had was a bad rear wiper motor around 60K miles.
I have seen the devices that can read the codes for about $70 at the local auto zone. I can do that by just turning the key a few times. How much would I need to spend on something that can read the voltages, do you have any suggestions on a good one to buy. I have a laptop computer that I could use if I could find the interface and software.
At one point the tech said something about a lazy O2 sensor. What would cause that?
I have been watching my milage via the overhead display. After the 02 sensor is replaced I will get around 15-18 MPGs for about 50-60 miles. After that the check engine light will come on and the milage will go down to 5-8 MPGs.
I have noticed that the trans was slipping a bit at startup, once I put it in drive it takes a couple of seconds before it goes. I check the fluid and that looks full. What would the trans have to do with the other problem?
I wish I would have paid by credit card, but it is a local shop and I paid by check. I have been documenting my issues, so I may go with small claims court. Right now I would just like to get it fixed without replacing the engine or spending another 2k.
C. E. White wrote:

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macdad wrote: > At one point the tech said something about a lazy O2 sensor. What

     If the Oxygen Sensor fails completely the Malfunction Indicator Lamp will go on and a Diagnostic Trouble Code stored in the Engine Control Module.
Some Oxygen Sensors are replaced because of degraded performance rather than outright failure. After some amount of use the Oxygen Sensor becomes "lazy". What is meant by "lazy" is that it does not respond to changes in the oxygen content of the exhaust stream as quickly as it should. The consequence is diminished engine power and increased fuel consumption. A "lazy" Oxygen Sensor does not set a DTC.
The sensor should swing between a low voltage (around 0.2 volts) and a high voltage (around 0.8 volts), and make this round trip about ten times per second. It takes a fancy meter (Fluke 87 or equivalent) to measure this, or an oscilloscope. There are also special-purpose electronic instruments which test Oxygen Sensors. You can't make an adequate test of an oxygen sensor with an ordinary voltmeter.
You may find a nice article about oxygen sensors at http://www.aa1car.com/library/o2sensor.htm
Daniel B. Martin
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Daniel B. Martin wrote:

Running rich and/or burning oil can contaminate an O2 sensor, making it "lazy" before its time. If you don't have excessive oil usage, perhaps look and see if you have a leaky fuel injector? Maybe time to pull the injectors and test the spray patterns?
nate
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macdad wrote:

Consider this:
http://www.obd-2.com /
A friend owns one of these and says it's wonderful.
Daniel B. Martin
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macdad wrote:

A volt-ohm meter reads voltages, and even a $10 _digital_ one is more than adequate.
An elaborate scan code reader doesn't read voltages but the stream of data put out by the car's computer that will include things like the oxygen sensor voltages, temperatures (air, coolant), air pressure, throttle position, fuel injector pulse widths. The cheapest I know of is similar to: www.andywhittaker.com/ecu/obdii_hardware.htm

O2 sensors gradually wear out or are damaged by contaminants or carbon. The tech should have shown you the voltage output, which for the front sensor should be roughly 1 volt, peak-peak, and a few hundred Hertz in frequency. The sensor behind the catalytic converter will put out a much weaker signal since the converter has removed so much free O2 from the exhaust.

The computer is detecting something wrong and putting the engine into limp mode, where some sensors are ignored and some settings, like ignition timing, are no longer varied but kept fixed. This should be easy to pinpoint because the Check Engine light comes on so consistently. Ask for the fuel pressure (raw and regulated), fuel pump delivery rate, and injector pulse width at idle, 2,000 RPM, and during real life cruising. Don't overlook things like bad wiring connections or leaking vacuum hoses.
You need to go to a different shop, preferrably an AAA approved one.
All I know about Chryslers is that you don't want the 4-speed automatic, but if you have it you must religiously use only ATF+3 or ATF+4 fluid and change it every 20,000-30,000 miles and not use Dexron with a friction modifier additive.
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Alldata sez on code P0171 you should:
* check coolant temp sensor, especially whether temp readings increase smoothly. If not, check for cooling problems and/or replace the sensor * examine freeze frame associated with P0171 for any abnormal sensor readings * perform general engine checks such as: engine vacuum (must be at least 13in in neutral), valve timing, compression, exhaust system, PCV system, engine drive sprockets, torque converter stall speed, power brake booster (check for vacuum leaks), fuel injectors.
I'd check that coolant sensor first. www.scantool.net is decent inexpensive ODB solution, and lets you read freeze frames.
Peter
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hows the trans shifting??/. trhere may be a issue with the trans and causing poor milage but so will driving at 70mph
macdad wrote:

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