P2099
Post Catalyst Fuel Trim System Too Rich (Bank 2)
Bank 2 counterpart of P2097. Post-catalyst trim on bank 2 has reached the rich limit — usually a depleted catalyst or a downstream sensor biased rich on the bank 2 side.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Symptoms
- Check engine light on
- Failed emissions inspection
- Possibly slightly increased fuel consumption
- Sulfur (rotten egg) smell from exhaust under load
Common causes
Ordered by how often each turns out to be the cause.
- Bank 2 catalyst oxygen storage exhaustedCommon
- Bank 2 downstream sensor biased richPossible
Parts involved
- Oxygen Sensor Downstream
- Catalytic Converter
P2099 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.