The engine computer has detected that the fuel mixture is too rich based on the readings from the downstream oxygen sensor on Bank 1. This indicates that there is an excess of fuel or an insufficient amount of oxygen in the exhaust stream after the catalytic converter.
The sensor may be skewed or biased, reporting a rich condition to the PCM even when the mixture is correct.
An injector that drips or stays open too long introduces excess fuel into the combustion chamber.
A failing regulator can cause fuel pressure to rise above specifications, forcing too much fuel into the cylinders.
A severely clogged air filter or intake obstruction can reduce air volume, resulting in a rich condition.
A malfunction in the control module's processing of sensor data or fuel trim logic, though this is rare.
Not necessarily. P2097 is a fuel trim code based on sensor readings, not a catalyst efficiency code (like P0420). However, long-term rich conditions can damage the catalyst.
While the downstream sensor is a frequent cause, replacing it without verifying fuel pressure and injector health may not solve the problem if the engine is actually running rich.
No. It is extremely uncommon for the PCM to be the cause of P2097. Exhaust and fuel system components should be thoroughly exhausted before considering a module replacement.