Trouble code
P2270
O2 Sensor Signal Stuck Lean (Bank 1 Sensor 2)
What P2270 means
The downstream oxygen sensor is stuck reporting lean.
Symptoms you may notice
- Check engine light
- Failed emissions test
Common causes, cheapest first
- Failed rear oxygen sensor
- Exhaust leak before the sensor
- Converter damage
Before you buy anythingFrequently appears with catalyst efficiency codes. Sort the exhaust leaks and the sensor before condemning a converter.
What to do next
- Confirm the code with your own scan tool, or have it read free at a chain parts store.
- Decode your VIN so you know your exact engine and build date.
- Work down the causes above from cheapest to most expensive.
- Search NHTSA for a recall or service bulletin covering this symptom on your vehicle.
- Read the engine buying guide before ordering.
P2270 is a generic OBD-II code, standardized across every make and model sold in the US from 1996 onward. The meaning is the same on any vehicle; the specific part and its location are not.
Parts
Parts commonly needed for P2270
These go to Amazon. We earn a commission if you buy, at no extra cost to you — see our affiliate disclosure. Which one you actually need depends on diagnosis — read the note above first.
Confirm fitment against your VIN on the listing page before ordering. A part that matches your year and model can still be wrong for your build date or engine code.