'99 XLS Po171 & P0174 codes

Here's a place that describes your trouble codes:

Thank you,

I will start looking for vacume leaks and clean the MAF first. Thanks again.

/Richard

Thank you,

I will start looking for vacume leaks and clean the MAF first. Thanks again.

/Richard

Let's just hope it's as easy to fix as it sounds like :-)

O2 sensor codes are often bad sensors, at least in my experience.

I have a PO136 and a PO141 on my '97 (4.0L OHV) and my brother-in-law-mechanic told me to check the voltage at the sensor. If the voltage is good then the sensor is bad.

OTOH I've had a CEL come on (same vehicle) and it went off after I cleaned the MAF, replaced the air filter, and cleaned the IAC (for good measure). It didn't come back on but in that case I didn't have a code reader available. Just dumb luck I guess.

Someday I would like to see a list of all the things that make the CEL come on so guys like me can at least try a few things before spending a bunch of money. Most of my Fords aren't worth paying someone to fix. It's kinda scary cause there isn't much input in this NG any more so I can only hope my luck continues.

Some how the concept that the voltage being right at the sensor dictates the sensor is bad is puzzling...

Could have been dumb luck, but what you did was sensible, and reasonable.

A scan tool is your friend. Personally I own my own scan tool (OK, I have *five* of them...) but many parts stores will scan for 'free'.

Frequently I can clear the DTCs for a vehicle and they won't come back on. This is always the best first start, certainly the cheapest one. Sometimes it is a transient problem, and it never reoccures.

It seems clear to me ;-) What I meant was if you have a code indicating a bad sensor and the wiring check out OK, and the proper voltage it getting TO the sensor, then the sensor must be bad.

My local parts stores used to scan for free but now they say the government won't let them do it any more. I guess the Auto Mechanics Union or somebody paid off the govment.

I've had results getting the CEL to go off by disconnecting the battery for a while but that was always when I did something like disconnect the throttle position sensor which should make the CEL come on. Sooner or later I'll have to get a code reader or start buying older cars ;-). Right now I have a '99 Ranger with auto trans problems and unfortunately I think I've eliminated all of the possible electronic and sensor problems so that leaves me with needing a rebuild/replacement. If I had a bad speed sensor would it show up as a trouble code? I have no codes and have had them read twice.

Perhaps misundertanding, but an O2 sensor generates voltage, and doesn't 'get' voltage. So if the voltage at the O2 sensor is right, then the sensor had to be good.

You must be in one of those states where you have no freedom at all. Like CA for example where you can't wipe your butt whtout running afoul of the law! They (scan tools) are not expensive, a good investment IMHO, especially if you live there!

Really old cars! Like from the 60's. But wait, taht won't work because some states are now forcing people to scrap these older, classic cars.

I guess more information about what's happening would be best. Is it a

OK then. I didn't know that. Now I understand what you meant.

You guessed it. I call it The Totalitarianism State. It's full of a bunch of brain-washed zombies that come from some place called "Back East" that believe whatever hogwash the government throws at them. AND they can vote. But seriously, if the government covered them with s*it and told them it was good for them, they would LIKE it and say "thank you."

I had a dream that they took away my '91 Explorer. I guess we're all supposed to buy a new car every two years. Maybe I should sell my '78 Ford pickup before they ban those. I've been told at the smog test place that they keep reducing the acceptable emissions but so far I've passed the smog tests no problem. Last year was supposed to be it's last smog test but they suspended the "30 year rollover" as they call it. I guess I won't be surprised if they do ban old cars/trucks. Hell, any state that can ban smoking OUTDOORS can do just about anything.

Well, it's a '99 Ranger Reg Cab, 2WD, 3.0L V6 engine, 4R44E auto trans, regular open differential, no transfer case, one-piece driveshaft. I don't even have a repair manual for it yet. Just got it a few weeks ago :-(

I cleaned the MAF (it didn't look like it needed it) and checked all of the hose connections I could find. It's been a week now and the CEL light has stayed off. I wonder if it was the extreme cold/wet this winter that tripped the light twice? Anyway so far so good!!!!

Good glad to hear its fixed. By the way, your engine is the 4.0 OHV. Its not "cheaper", it might be less powerful than the SOHC or the V8, but it is a reliable bullet- proof engine.

Yes! I have three of those engines.

That's good to hear! I hope the light stays off but we will see in a couple of weeks when he comes back from school. Thanks again for all of the help.

It's been over a month and the light has not came back on!!!!!!!