My son drives a 2005 Chevy Trailblazer EXT with a 4.2L in it. He tells me that his check engine light came on. Of course it did. Another thing for dad to work on. He took it to AutoZone



to have it scanned. That didn't say much other than he had a P0171 error code. It says it could be an oxygen sensor. We decided to buy an OBDII scanner. I have worked on cars a long time ago and figured we could do this (meaning I do the work and my son holds the light). I have heard that it could be the Mass Air Flow sensor, but It appears my vehicle does not have one. The air filter is new and we took the throttle body off and cleaned that up. Since I do not know how to read these new scanners very well, I am trying to figure out if it could be a fuel pressure problem, and I need to drop the gas tank and replace the fuel pump; an oxygen sensor problem, or if I need to replace the catalytic converter. It seems that the light can go off and come on randomly and typically shows up around 30-40 mph. I have attached the read out from the OBDII. Any help would be greatly appreciated.