Code P0172

[lipunx]

Greetings,
My car is throwing me code P0172 - Fuel Trim,Bank 1 System too Rich. Is this a sign of a dirty maf ? Or are my o2 sensors on there way out ?

Thanks in advance everyone here is always very helpfull.

[Mr_Diesel]

Greetings,
My car is throwing me code P0172 - Fuel Trim,Bank 1 System too Rich. Is this a sign of a dirty maf ? Or are my o2 sensors on there way out ?

Thanks in advance everyone here is always very helpfull.

What car/engine do you have? If it knows it's running rich, I would assume it's getting that information from the O2 sensors... Which could mean, that either the 02 sensor is functioning properly and it is running rich, or the o2 sensor is bad and sending a wrong signal...

[lipunx]

98 Jetta with a 2.0 . I also just relized it only comes on after I fill the car up with gas engine on or off I still get the cel.

[Mr_Diesel]

98 Jetta with a 2.0 . I also just relized it only comes on after I fill the car up with gas engine on or off I still get the cel.

How's the rubber seal on the gas cap? I heard that OBD II vehicles pressureize the gas tank or something... I have heard more than one instance where a faulty gas cap has lead to a CEL.

[lipunx]

I'll check it out and let you know. That may be it but the car also is'nt as smooth as it should be. I had another Jetta which was a 97 and changed both o2 sensors and what a difference it made. However I only changed them because they failed which is not the case here. They could be on there way out or atleast one of them.

Ps The 97 got smashed by some kid who blow a stop sign in front of me.

[lipunx]

I checked the cap and it looks just fine. I just dont understand lol.

[burn_your_money]

It's a stretch, but depending on where you live/gas up maybe your car doesn't like the winterized gas.

Have you tested your O2 sensors?

[speedbump]

98 Jetta with a 2.0 . I also just relized it only comes on after I fill the car up with gas engine on or off I still get the cel.

How's the rubber seal on the gas cap? I heard that OBD II vehicles pressureize the gas tank or something... I have heard more than one instance where a faulty gas cap has lead to a CEL.

I don't know about all OBD II, but I know that most do. It's so the computer can detect leaks in the evap system. On my Blazer, if the gas cap is loose/missing the service engine light will blink.

Most auto makers recomend changing O2 sensors every 30k miles. 8O

Another possable cause of running rich could be a bad fuel pressure regulator. It's very rare that they go bad, but I had one go bad on my Vanagon. Their should be a valve on the fuel rail for hooking up a pressure guage. Also check the vacuum hose going to the regulator, too little vacuum will increase fuel pressure. The amount of fuel an engine gets (EFI) is determined by how long the injector is open and the fuel pressure.