P2240
O2 Sensor Positive Current Control Circuit/Open Bank 2 Sensor 1
Fuel & air metering
Generic OBD-II
Medium
What it means
P2240 means the PCM has detected an open or fault in the positive current-control (pump) circuit of the upstream wideband oxygen sensor on bank 2, sensor 1. This circuit lets the sensor measure the air-fuel ratio, so when it's open the ECM loses accurate feedback and fuel trim drifts, causing rough running and higher fuel use.
Medium
Can I keep driving? Driveable, but with the upstream sensor offline fuel trim suffers, so expect rougher running and higher consumption until it's fixed.
Common symptoms
What you'll notice
- Check-engine light on
- Rough idle or uneven running
- Higher fuel consumption
- Occasional engine surge or hesitation
Common causes
Most likely first
- Faulty upstream (bank 2, sensor 1) wideband/air-fuel oxygen sensorLikely
- Open or short in the O2 sensor's positive current-control (pump) circuitCommon
- Poor connector contact or corrosion at the sensor plugCommon
- Chafed or damaged harness near the exhaustLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and check for companion O2 control codes (P2237, P2241, P2242).
- Inspect the bank 2 sensor 1 connector and wiring for corrosion, melting, and chafing near the exhaust.
- Check the positive current-control circuit for continuity and for an open or short against spec.
- Rule out intake or exhaust leaks near the sensor that can skew its operation.
- If the wiring is good, replace the upstream oxygen sensor as specified.
FAQ
Quick answers
Is it safe to drive with P2240?+
Short trips are fine, but with the upstream sensor's control circuit open the ECM can't fine-tune fuel, so it runs richer and less efficiently. Fix it before it wastes fuel or fouls the converter.
Can I just clear P2240?+
It returns once the ECM tests the circuit again unless the wiring or sensor is repaired.
Related codes
Often seen with P2240
Read & clear P2240 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