Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[terry paget]

Petrol 2.2 manual saloon
My son Jonny, to whom I gave a £10 code reader to cancel his weekly EML illumination with code P420 read out, reports a new code, P180 fuel trim. What does that tell me?

[Chazza12]

fuel trim is it can be running rich or lean.

Run engine at 2500 rpm to test.

Running too rich – High negative fuel trim corrections can be caused by MAF sensor problems, high fuel pressure, leaking fuel pressure regulator diaphragm, faulty evaporative emissions components, leaking injectors, defective O2 sensors, exhaust leaks/pinholes before the O2 sensor, coolant temp sensor problems, and base engine issues such as low compression and incorrect camshaft timing.

Running too lean – High positive fuel corrections can be traced to MAF and O2 sensor faults, vacuum leaks from intake gaskets/hoses, unmetered air (intake snorkel leak), clogged or dirty fuel injectors, fuel delivery issues, and exhaust restrictions such as a clogged catalytic converter.

[TheBoy]

The ECU's calculations of air coming in, fuel coming in, engine load and oxygen readings in the exhaust are implausible.

Start by looking for air leaks in intake or exhaust.