P2240

O2 Sensor Positive Current Control Circuit/Open Bank 2 Sensor 1

Q: 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.

Q: Can I just clear P2240?

It returns once the ECM tests the circuit again unless the wiring or sensor is repaired.

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.

Real-world scan data

Seen in

scans in the past year

Found in

<0.1%

of scans

<0.1%

of scans that found faults

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

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.

Read & clear P2240 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX