My wife's check engine light just came on and after hooking up the code reader, I got codes P0171 (system to lean) and P0521 (Engine Oil Pressure Sensor/Switch Range/Performance).
Not sure if they are some how related or it was just a coincidence.

Has anyone had these codes pop up and what were the culprits?


Thanks,
Sal

 

P0171 can be caused by:

- Restricted fuel supply line
- Fuel pump inlet strainer plugged
- Fuel pump module
- O2 signal circuit
- O2 return circuit
- O2 sensor heater operation
- O2 sensor
- MAP sensor operation
- ECT sensor operation
- Engine mechanical
- Fuel filter/pressure regulator
- PCM (Powertrain control module)

P0521 can be caused by:

- Engine oil/engine mechanical
- Excessive resistance in the (G6) engine oil pressure sensor signal circuit
- Excessive resistance in the (F855) 5-volt supply circuit
- Excessive resistance in the (K900) sensor ground circuit
- Engine oil pressure sensor
- PCM

The only obvious common link between the two codes is the PCM -- I hope that's not the problem.

 

Update...

I removed and and cleaned the MAF sensor which was dirty and a few days later the check engine light cleared and has not came back on again, it has been about two months now.
I also did an oil/filter change that same day so I am not sure which of the two or if both actually contributed to the clearing of the check engine light.

One more thing, I have not hooked up a code reader to see if the codes are still there.