Help diagnosing codes....
On The Tree
Joined: May 2003
Posts: 106
Likes: 1
From: Apache Junc, Az
Re: Help diagnosing codes.... Code P0172 and P0175 is most often caused by a bad fuel pressure regulator or a bad fuel injector. You will need to do a fuel pressure test to determine which is exactly the problem.
It may have too much pressure or good pressure but leaking down into engine due to a bad injector or pressure regulator.
Also; the MAF sensor might be contaminated from: dirt, oil, silicon, spider webs, potting compound from the sensor itself, etc. When a MAF sensor gets contaminated it skews the transfer function such that the sensor over-estimates air flow at idle (causes the fuel system to go rich) and under-estimates air flow at high air flows (causes fuel system to go lean). This means Long Term Fuel Trims will learn lean (negative) corrections at idle and learn rich (positive) corrections at higher air flows.
This malfunction may or may not throw a DTC (Diagnostic trouble Code). If it does, the possible DTC's are: P0171, P0172, P0174, P0175.
It may have too much pressure or good pressure but leaking down into engine due to a bad injector or pressure regulator.
Also; the MAF sensor might be contaminated from: dirt, oil, silicon, spider webs, potting compound from the sensor itself, etc. When a MAF sensor gets contaminated it skews the transfer function such that the sensor over-estimates air flow at idle (causes the fuel system to go rich) and under-estimates air flow at high air flows (causes fuel system to go lean). This means Long Term Fuel Trims will learn lean (negative) corrections at idle and learn rich (positive) corrections at higher air flows.
This malfunction may or may not throw a DTC (Diagnostic trouble Code). If it does, the possible DTC's are: P0171, P0172, P0174, P0175.
