My car is showing a P0172 obd2 code for mixture being too rich. I have cleaned the mass air flow sensor and replaced some vacuum lines, but code still comes back. Before it was setting a rich code it was setting a purge valve solenoid code, but the code for that one has disappeared. Does anyone have any idea's on what could be causing this?

 

My guess is one of the 02 sensors is bad. For one reason or another the engine is not getting enough air. There could be a restriction somewhere also

 

I have checked the volts on the two oxygen sensors upstream, they both have the required volts on warmup. The thing is I just did replace one of the 02 sensors upstream about 1 month ago.

 

Measuring the voltage doesn't tell you much. You need to watch the o2s switch on the computer and watch the fuel trims to see what is going on.

 

I checked the long term fuel trim its way off from normal, its like -21.00%.

 

That is way off. Is this only on 1 bank?

 

Not real sure, the scanner I got shows two different ltft but only says bank 1. I'm getting another scanner sunday (a better one) to retest it.

 

I replaced my air filter on my cold air intake, it had a disposable filter on in it from the previous owner. I replaced it with a k&n. I erased the dtc's once again to check it. After driving again it yesterday,the check engine light came back on. I checked it with my new scanner. I'm not showing a running too rich code anymore, it's now showing a P1443 code. Something about the Evaporative Emission Systems Purge Flow was low or no flow at all.

 

Lol have fun with that one... evaporated leaks and purge systems are hard to work with...

 

Got it fixed. It was a purge flow sensor.

 

Great job!!