P2273O2 Sensor Signal Biased/Stuck Rich (Bank 2, Sensor 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
- P2273 means the rear oxygen sensor of bank 2 keeps a high voltage when the exhaust of that bank should be lean. GM's 2016 tables (16OBDG05) check this in fuel cut-off and set the code if the signal is above 100 mV after 9 g of air (Type B); GM's 2024 tables (24OBDG07) compare the lowest voltage during a commanded lean phase with 0.20 V over two trips. The Bosch-based 2005 GM V6 leans the bank after a long high-voltage phase and also fails the sensor above 0.202 V four seconds into a fuel cut. Ford treats bank 2 like bank 1 and uses fuel-cut events from model year 2019. Typical causes are a sensor fouled by oil or coolant on that side or a signal wire touching a supply line. P2099 is the post-catalyst trim of bank 2 at its rich limit; P0158 a voltage above the normal range.
- What you may notice
- Malfunction indicator lamp on
- Catalyst monitor for bank 2 not completing
- Likely causes
- LikelyBank 2 rear oxygen sensor fouled by oil or coolant
- RareSignal wire touching a supply or heater line
- RareBank 2 front sensor misreading so that the bank actually runs rich
- 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: €60 – €350
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.