P2097 · Post-catalyst fuel trim system too rich, bank 1
The computer’s fine-tuning from the oxygen sensor behind the catalytic converter reached its limit in the rich direction on bank 1. The exhaust after the converter kept reading rich even after the computer pulled fuel away.
Part of the Fuel trim system guide.
How it differs from P2096
Both codes come from the same downstream correction. P2096 means the computer ran out of room adding fuel. P2097 means it ran out of room taking fuel away. The two codes call for different checks, so copy the number exactly.
What a shop should look at
Ask how the downstream sensor reading compares with the upstream sensor when the engine is warm and steady. Ask about the main fuel trims and any misfire counts. A converter that no longer stores oxygen well, a sensor problem and an engine that runs rich can all affect that reading. The vehicle procedure tells the technician which tests separate them.
A vehicle-specific example
On the 2018–2019 Volkswagen Atlas 3.6L vehicles covered by bulletin 01-20-01, P2097 is one of the listed codes. The repair replaces the converter and updates the engine software, and the bulletin says to do that before diagnosing the listed codes another way. Check your VIN before applying it.