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.
Medium severity. Can I keep driving?Yes, you can normally drive in moderation, but get it repaired soon: you will use more fuel and the catalytic converter can be damaged over time.
Bank 2 is the side without cylinder 1, so it only exists on V or boxer engines. Sensor 2 is the sensor after the catalytic converter.
Symptoms
- Malfunction indicator lamp on
- Catalyst monitor for bank 2 not completing
Most likely causes
- Bank 2 rear oxygen sensor fouled by oil or coolant
- Signal wire touching a supply or heater line
- Bank 2 front sensor misreading so that the bank actually runs rich
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: medium
- It affects emissions.
What each character of P2273 means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- 2: Fuel injection
- 73: Specific fault in that system
Frequently asked questions
Can I keep driving with code P2273?
Yes, you can normally drive in moderation, but get it repaired soon: you will use more fuel and the catalytic converter can be damaged over time.
What causes code P2273?
The most common causes are: bank 2 rear oxygen sensor fouled by oil or coolant; signal wire touching a supply or heater line; bank 2 front sensor misreading so that the bank actually runs rich.
Related codes
- P2272O2 Sensor Signal Biased/Stuck Lean (Bank 2, Sensor 2)
- P2271O2 Sensor Signal Biased/Stuck Rich (Bank 1, Sensor 2)
- P2099Post Catalyst Fuel Trim System Too Rich (Bank 2)
- P0158O2 Sensor Circuit High Voltage Bank 2 Sensor 2
- P013CO2 Sensor Slow Response - Rich to Lean Bank 2 Sensor 2
- P2198O2 Sensor Signal Biased/Stuck Rich (Bank 2, Sensor 1)
Sources
- gsi.ext.gm.com: 16OBDG05 Engine Diagnostics
- gsi.ext.gm.com: 24OBDG07
- gsi.ext.gm.com: 2005file14
- fordservicecontent.com: OBD Operations Summary Gasoline 2020 2023
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.