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View Full Version : CHECK ENGINE LIGHT came on code: P0171



broderp
07-17-2009, 06:21 PM
As the title says, my check engine light came on in my 2003 Celica on the way to work.


The Autozone guys plugged it up and here is what they say:

P0171 (code)

AIR/ FUEL MIXTURE LEAN BANK 1

1-LOW FUEL PRESSURE
2-FAULTY MAF/VAF SENSOR
3-CYLINDER MISFIRE CONDITION
4-FAULTY H02S/AF SENSOR
5-LARGE VACUUM LEAK




My symptoms so far are:
1. Slight hesitation on acceleration
2. engine doesn't like rev as free as it did
3. feels like it's going to back fire, but it has not
4. slight smell of sulfer..very slight


Car starts right up, idles just fine, even with AC on.


I just got this car, so I'm a bit bummed this sort of thing is happening already. I sunk all my money on this car so I wouldn't have a car payment, so I am broke for a few months. But its now my only car. :wedge:

Any pointers, ecperiences? I'm heading over to the BGB section to seewhat I can actually test myself.

Mafix
07-17-2009, 06:35 PM
mass air time. try cleaning it first.

broderp
07-17-2009, 07:40 PM
mass air time. try cleaning it first.

Stupid question: Does it come out fairly easy? This is my first 7th gen and I'm seeing a lot of plastic and rivets and NOTHING looks familiar!

Second, I recall taking the meter off my MR2 years ago and spraying the crap out if it with carb clreaner until it was all silver and shiny with the little "flapper thing" as smooth and free as I could get it. Same thing?


thanks!

Kastigir
07-17-2009, 07:43 PM
First I'd go ahead and reset the code and see if it returns. Then start troubleshooting. If it was a random misfire, it could've already fixed itself.

Mafix
07-17-2009, 08:50 PM
it's not a misfire. stupid autozone scanner. bank 1 lean code. mass air issue.
this vehicle does not have the AFm it has a MASS AIR. it's a little black box on the intake tube. held in with 2 screws.

broderp
07-17-2009, 09:54 PM
it's not a misfire. stupid autozone scanner. bank 1 lean code. mass air issue.
this vehicle does not have the AFm it has a MASS AIR. it's a little black box on the intake tube. held in with 2 screws.


found it, well at least in the BGB. I will take apart and clean. Can I resest the code by unplugging the battery?

broderp
07-18-2009, 01:49 AM
Two things....

I think I fixed it, you guys were correct. The sensor didn't look as bad as I thought it would, but cleaned it with throttle body cleaner (all I had).

But I noticed that I had inadvertenly re-installed my air filter cover wrong. (the day before) I guess you could say it was not really on at all. I suppose it may have been sucking in a lot more air than what it was suppose to.

Does the ECU not reset the MIL? I replaced the cleaned MAF sensor, properly reinstalled my air filter cover and the CEL was still on.

I started my car and could INSTANTLY feel and hear the improvement, but the light was still on.

Autozone refused to reset the light, saying they could get into trouble. They said when I fixed the problem, the light would go out. (It never did) I took a chance and disconnected my battery for a few minutes and restarted the car and THE LIGHT STAYED OFF!! :Ban1:

DOes the ECU reset the light? or does it need to be reset manually? I think Autozone wanted me to buy a MAF or O2 sensor (of course I couldn't return if I used them) and in this case, I don't seem to have needed anything.

Kastigir
07-18-2009, 02:10 AM
OBD2 cars are continually scanning the sensors, so theoretically it should reset once the problem is fixed. You could pull the battery cable for a minute and do the same thing.

CollapsedNut
07-18-2009, 02:41 AM
Wow thats lame of them. I;ve worked for many advanced autos and I've never heard of any thing about not being able to reset a light. They just wanted you to buy the part. Or were to lazy to go reset your ecu.

broderp
07-18-2009, 01:34 PM
Lame isn't what comes to mind. but I'll be polite! They did give me a free diagnostic of the code which got me started in the right direction.

The lady who did it (no offense to the good lady mechanics out there) really doesn't look like she knows much about cars. Asking her general questions gets really basic and non-specific type answers. BUt they are there to sell parts and that she was good at. (trying to get me obuy a MAF or o2 sensor.....)