P2097 Post Catalyst Fuel Trim System Too Rich (Bank 1)

P2097 sets when the downstream (post-catalyst) fuel-trim correction on bank 1 runs too rich — the exhaust past the converter reads richer than expected and the module cannot trim it back into range.

Code details

Generic OBD-II · P2

System: Fuel / Air
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not condemn the converter or rear oxygen sensor before checking for a rich cause upstream, since the downstream reading follows what the engine actually delivers.

Symptoms of P2097

Check-engine light.
Possible rich smell, sooty tailpipe, or rough running.
Worse fuel economy.

Common causes of P2097

Leaking injectors or high fuel pressure.
A contaminated MAF or a biased oxygen sensor.
A restricted air filter or intake.
An upstream fuel-trim fault feeding the converter rich.

Useful checks before replacing parts

Compare upstream and downstream oxygen-sensor signals and fuel trims.
Check for leaking injectors, high fuel pressure, or a contaminated MAF.
Inspect for engine oil or coolant contamination reaching the exhaust.

Related OBD-II codes

These nearby fuel / air entries can help compare wording and pin down the fault area.