P0175 — System Too Rich Bank 2

Fuel trims indicate a rich tendency on bank 2: the controller removes fuel to compensate. Bank 2 is the cylinder group that does not contain cylinder 1. The code alone does not prove oxygen-sensor failure; identify the real or reported mixture problem.

Affected system: Powertrain

Symptoms

• Uneven idle, hesitation or reduced power.
• Engine warning light; consumption may rise, with fuel odor or black deposits possible.

Possible causes

• Leaking injector, excessive fuel pressure or excessive EVAP vapor flow.
• Inaccurate MAF/temperature/oxygen-sensor information; one or both banks may be affected.

What to check

• Locate bank 2 and save RPM, load and temperature; address related sensor or misfire codes first.
• Compare both banks’ STFT/LTFT at idle and moderate load with the engine warm and fuel control active.
• If only bank 2 is affected, check its injectors for leakage and evaluate the plausibility of its oxygen-sensor input.
• Check fuel pressure and EVAP purge operation; confirm the enrichment cause by measurement before replacing parts.
• After repair, clear codes and recheck both banks’ fuel trims under the original recorded conditions, following the manufacturer’s procedure.

Also written as: P0175-00, P017500, PO175 (some scan tools add the fault-type byte, e.g. -00).