P2238
O2 Sensor Positive Current Control Circuit Low Bank 1 Sensor 1
Fuel & air metering (O2 sensor)
Generic OBD-II
Medium
What it means
P2238 means the ECM detected a low-voltage condition in the positive pump-current control circuit of the upstream wideband air-fuel (O2) sensor on bank 1, sensor 1. This circuit lets the sensor measure the exhaust mixture; with it faulted the ECM runs open-loop, so the car stays drivable but may idle rough and use a little more fuel until the sensor or wiring is fixed.
Medium
Can I keep driving? Drivable — with the upstream sensor circuit faulted the ECM runs open-loop, so expect slightly worse economy and possibly rough idle, but no stalling risk.
Common symptoms
What you'll notice
- Check-engine light on
- Slightly rough or uneven idle
- Increased fuel consumption
- Minor hesitation or surging
Common causes
Most likely first
- Faulty upstream air-fuel ratio (wideband O2) sensor, bank 1 sensor 1Likely
- Low voltage / short-to-ground in the sensor's pump-current control wiringCommon
- Poor or corroded connection at the sensorCommon
- Faulty ECM/PCM driverLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame and check for companion sensor codes (P2237, P2239, P2231).
- Inspect the bank 1 sensor 1 connector and wiring for corrosion, chafing, or exhaust-heat damage.
- Check the pump-current control circuit for a short to ground or high resistance.
- Confirm the ECM is supplying the correct control signal to the sensor.
- If the wiring is good, replace the bank 1 sensor 1 air-fuel/O2 sensor and retest.
FAQ
Quick answers
Is it safe to drive with P2238?+
Yes, for the short term. The car runs in open-loop with slightly worse economy, but there is no stalling risk; repair it before it affects emissions or the catalyst.
Can I just clear P2238?+
It returns until the sensor or its current-control circuit is repaired, since the ECM monitors that circuit whenever the sensor is active.
Related codes
Often seen with P2238
Read & clear P2238 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX