Hi folks. I've searched the forum. My head is spinning! I just had a major repair done to my 04 SE when the head gasket failed. Heads were sent out, engine was taken down to short block, de-sludged, and all gaskets replaced. Also Fuel injectors were cleaned. Within a few miles, I got a check engine light. I pulled P0171, P0174, P1171, P1174. I can tell from this forum what the codes mean individually, but not sure as to what they mean collectively, or where to start in the troubleshooting process. Any guidance would be greatly appreciated. Thank You!

 

first off make sure that your o2 sensors were plugged back in. or are plugged in snuggly. as well as your MAF. check these connections first. clear the codes and go for a drive.

 

So those codes mean one or more of three possibilities.

a. not enough fuel in the system
b. unmeasured air into the system
c. a bad sensor

a. fuel pressure ... least likely, but possible, test is to measure the pressure, likely cause bad fuel pump, something in the system.

b. unmeasured air means a vaccum leak, test is s smoke test, cause, any vaccum leak, could come from a bad gasket seal, or from a vaccum line not hose clamped down.

c. bad sensor, it is either the MAF sensor or a O2 sensor, usually a bad 02 has other codes as well.

 

Thanks for the replies. I'm on it! After reading through forums, I found the best prices for Bosch O2 and MAF sensors on amazon.com, and plan to replace those regardless due to the mileage. But first...the smoke test!