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Ford Taurus 2003 OBD code P0172

Hi all

I have a 2003 Ford Taurus. It has been running rough for awhile. It doesn’t happen all the time, alas. I took it to my local repair guy. They first said, oh this happens when the AC is on. But I knew it happened otherwise.

The check engine light came on yesterday, blinking, but didn’t stay on. And it was running rough. Check engine light came on, on a Sunday so I had to wait until Monday to bring the car in. They just called and said they can’t find anything wrong, ran it on the computer, says it’s running fine. I said, did you check the spark plugs, wires, etc? (I am good at googling, to be armed with some kind of info)

I am thinking they just put it on the computer. I suppose it has to be running bad to show anything (?) and even then, it’s no guarantee. Anyway. It seems like I am “sentenced” to driving this car until it strands me, catches on fire (I read about that possibility and I have on occasion smelled something burning), or if luck has it, when it is running rough, and I bring it in while it’s running rough, the computer finds the problem.

I do not find all of this very acceptable? Any suggestions? Am I being overdramatic?


the onboard diagnostic (odb2) should store problems in it’s memory whether or not it is happening at the time of the test. unless you’re having a problem with the battery going dead or something like that, the computer should tell you what WAS wrong even if it’s not wrong anymore. if there was a problem that only happened once or twice, the odb will still store the fact that it happened. it doesn’t know everything. it’s just a stupid computer and will only see what the manufacturer has put sensors on. you might simply have a loose wire that made it blink and the problem of running rough is something completely different. i would try to pinpoint the problem a little better. is it starting rough, or only acting weird after it’s on? what is or isn’t happening? is it accelerating properly but idling rough? what were the driving conditions? have you hit anything lately? running rough is a little vague, it could mean the engine or something like bad alignment. of course, it probably goes without saying, but does this happen when you’re almost out of gas? how’s your fluids? a little more information is needed. if your CEL did come on and they didn’t find anything when they plugged it in, find a new mechanic quick! a two year old can use one of those. if they can’t you shouldn’t take it there to get a tire changed let alone deal with anything more complex.
mechanics aren’t psychic and haven’t been driving your car. you need to give them as much info as possible, otherwise, they’re going to try to throw all kinds of stuff at it and it’ll end up costing you a fortune for something that could be as simple as a clogged filter.

It’s been happening for at least a couple of months, but as I said, it’s not all the time, and it seems like it’s happening more frequently. I had first noticed something wierd when I shifted into drive - you know how the car starts moving when you put it into drive? Now, it just sits there until I accelerate.

Sluggish, rough, it feels like the engine is missing, seems like it is not firing on all cylinders. Not purring, not idling smoothly, not running smoothly - like it’s all clogged up and needs to be cleaned out.

In general, I do notice when I’m driving. One time I accelerated, and it shifted to a higher gear and ran better! That surprised me.

Not when I’m almost out of gas - I do not let it go that far. I have it serviced regularly so fluids have been checked (last time I had oil changed).

BTW, my trans went a little over 1 year ago, if that means anything.

I like to give the small town guy my business. Yes he is a tire dealer but in the past, the mechanic has been good (this could have changed). I did have my suspicions as to whether they wanted to deal with this or not. And, I abhor car dealers and mine in particular (closest to me). I may have to bite the bullet on this and go there anyway - hopefully when it’s running rough to give them something to work with, and before a fire occurs. I’ve been thinking of getting a new car (esp w/ trans going last year) - just can’t make a decision as to what.

From the reading I did, I knew figuring this out was not going to be easy. I thought the check engine light going on was going to be more helpful. I guess I just need to continue driving and wait and see. Not a very reassuring thought if I’m far from home though.

the tranny could have something to do with it, but i don’t know that much about them, so i’ll leave that up to someone else. if it misfires, there should be a code on the odb. maybe it is just “clogged up” fuel filters do need to be changed regularly. shifting into higher gear and then a smooth run does make it sound like a fuel issue to me (well or a tranny issue, but yours is new). is there any smoke or smells or noises? does it backfire when you start it? did you notice of the dash lights dim more than they used to when you put it into gear? I think you’re right, bite the bullet. if you catch it now, it might not be that bad. If it is, always remember you can politely decline to fix it.

No backfiring. No smoke. No odd noises. I haven’t noticed dimming of dash lights (but will look for it).

I have smelled the smell of something having been burned when I get out of the vehicle on a few occasions. I don’t do a whole lot of driving. I work from home, run local errands. My biggest ride is usually 15 minutes and mostly stop and go w/ some 50-55 MPH spurts.

What do you mean by fuel issue?

I found out how trans are a whole 'nother deck of cards. I had thought of getting rid of the car after the trans went - went to AAMCO, only 1 year warranty which is now over. Didn’t have a lot of confidence in them. Wish I had taken it to local trans guy who would have given me a 2 year warranty. You live and you learn!

You need to get the actual error codes out of it. As noted, they will be in there. If the light isn’t on when read they should be in there as “history” codes. The codes look like “P1234” - find someone who can pull your history codes (not all tools do it), write down the exact codes and post them. Do not drive the car with the engine light flashing.

Until then its just a game of checking common things. Someone needs to put a fuel pressure gauge on it & check it under load. How old are the plugs & wires? Fuel filter? Air filter? If any of this is old, have it dealt with - if the plugs get changed someone should check the compression in the process.

Update. The car was running better. Now this week, the check engine light came on and stayed on (about 3 days now). I had a parts store check the code for me. I have a P0172 (bank 1 system too rich). Now, googling around about this code - it seems like it could become a crapshoot as to whether they find and fix the problem, and I could be many monies and several visits down the road trying to get to the bottom on it (it seems people who know cars, work on cars have a laundry list of possibilities). But any more advice would be helpful. How to best find a good mechanic that would take it on (other than dealer of course), find/resolve without costing a fortune. It sounds like a pain of a problem to solve. And is it worth it? Even getting a new car (would they take this car as a trade in - with the check engine light on?) which I’ve thought about I just can’t make up my mind what I want.

Cheers all, and good times.

Its not a crap shoot for a decent mechanic. Rich/lean running is a very basic engine issue that should be a mystery to no one. One thing you could probably do yourself for about $6 is clean your mass airflow (MAF) sensor.

Other than that, the best way to find a decent mechanic is by word of mouth. Just start asking around among reasonable people that you know. They should begin with a look at what the bank 1 oxygen sensor is doing, do basic check/inspection of the fuel system & look for vacuum or exhaust problems that might throw off what the O2 sensor is doing. This will cost some diagnostic $$ but if you start with asking around & find a trustworthy shop you should at least get a fair shake.