P2238O2 Sensor Positive Current Control Circuit Low (Bank 1 Sensor 1)
- 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
- P2238 is the low-side fault of the pump-current circuit of the front wide-band sensor on bank 1. Saab's 9-5 2.0 turbo (2010) shows a concrete test: on overrun with the injectors shut off, pure air should drive the signal well above its stoichiometric level, and if it stays below 1.7 V for 3 s the code sets as Type B. GM's 2005 V6 tables use the same fuel-cut check but book it under P2237. Mitsubishi's 2022 Outlander lists P2238 as a two-trip code. Ford does not use it at all: a pump-current wire shorted to ground lands in P0131 there. P2237 is the open circuit, P2239 the high-side fault, P2241 the same on bank 2. Typical findings are a grounded IP wire or a sensor that can no longer pump oxygen.
- What you may notice
- Check engine light after two drives
- Lambda value does not rise during coasting in live data
- Likely causes
- LikelyPump-current wire chafed through to ground
- PossibleAged or contaminated sensor that no longer reads lean in fuel cut-off
- RareFault in the sensor interface of the ECM
- 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: €80 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.