P2099Post Catalyst Fuel Trim System Too Rich (Bank 2)
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P2099 is the bank 2 counterpart of P2097: the rear oxygen sensor of bank 2 keeps reporting lean exhaust, so the post-catalyst trim of that bank adds fuel until it reaches its rich-side limit. Ford sets it 5 s after the bank 2 rear bias trim reaches +0.087, with the closed loop running, coolant between 160 and 250 °F and at least 15 % fuel in the tank; GM's Bosch-based 2005 2.8 and 3.6 V6 and the 2008 3.6 LLT list it as a lean shift of the secondary trim beyond its calibrated limit, over two trips. A typical physical cause is air drawn into the exhaust ahead of the bank 2 rear sensor, at a cracked manifold, a leaking flange or a loose sensor, which makes that sensor read lean. A rear sensor that has aged lean or a front sensor reading rich gives the same result. Check fuel trims and front sensor data of both banks before replacing a sensor.
- What you may notice
- Malfunction indicator lamp on
- Slightly higher fuel consumption
- Likely causes
- PossibleExhaust leak ahead of the bank 2 rear sensor
- PossibleBank 2 rear oxygen sensor skewed lean or aged
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €0 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.