P2251

O2 Sensor Negative Current Control Circuit/Open Bank 1 Sensor 1

Q: Is it safe to drive with P2251?

Yes for short trips, but fuel control and emissions are affected while it's active, so schedule the repair before longer driving.

Q: Can I just clear P2251?

You can, but an open in the current-control circuit or a failing sensor will set it again.

Fuel & air metering (O2 sensor) Generic OBD-II Medium

What it means

P2251 means the negative pump-current control circuit for the bank 1, sensor 1 wide-band oxygen sensor is open or faulty. Wide-band air/fuel sensors rely on a small controlled current to measure the mixture accurately, so an open here leaves the ECM without a usable reading and upsets fuel trim. It's typically a broken wire, a corroded connector, or a failing sensor.

Medium

Can I keep driving? Drivable, but a faulty wide-band O2 sensor throws off fuel control, hurting economy and emissions and possibly causing rough running; repair soon.

Real-world scan data

Seen in

237

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 or uneven idle
Increased fuel consumption
Engine surge or hesitation

Common causes

Most likely first

Faulty wide-band (air/fuel ratio) oxygen sensor on bank 1, sensor 1Likely
Negative current-control wire open or brokenCommon
Poor connection or corrosion at the O2 sensor connectorCommon
Wiring damage where the harness routes near the exhaustLess often

How to diagnose & fix

Work through it in order

Read freeze-frame data and check for companion bank 1 O2 codes (P2237, P2252).
Inspect the bank 1 sensor 1 connector and wiring for corrosion, chafing, or a broken conductor.
Check the negative current-control circuit for an open or high resistance against spec.
Confirm the sensor's reference and ground circuits are intact.
Replace the wide-band O2 sensor if the circuit tests good but the fault stays, then clear and re-test.

FAQ

Quick answers

Is it safe to drive with P2251?+

Yes for short trips, but fuel control and emissions are affected while it's active, so schedule the repair before longer driving.

Can I just clear P2251?+

You can, but an open in the current-control circuit or a failing sensor will set it again.

Read & clear P2251 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