Error code

OBD2 P2251

OBD2P2251
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.

What it means

O2 Sensor Negative Current Control Circuit/Open.

Severity

moderateCan drive but may experience increased fuel consumption and readiness monitor issues.

Summary

P2251 indicates an issue with the negative current control circuit of the upstream oxygen sensor (bank 1) on your vehicle's engine.

Symptoms

  • Illuminated warning light
  • Increased fuel consumption
  • One or more readiness monitors may not initiate or complete

Common Causes

  • Burnt, damaged, shorted, disconnected, or corroded wiring and/or connectors
  • Defective or malfunctioning upstream oxygen sensor
  • Use of unsuitable, incorrect, or substandard aftermarket oxygen sensor
  • Failed or failing PCM (Powertrain Control Module)

Diagnosis

  1. Check wiring and connectors for damage, corrosion, or disconnection.
  2. Inspect the upstream oxygen sensor for defects.
  3. Verify correct installation of any aftermarket sensors.
  4. Test PCM functionality if other causes are ruled out.

Fixes

  • Replace damaged wiring/connectors
  • Install a new upstream oxygen sensor
  • Replace the PCM if it is faulty

FAQ

What does P2251 mean?

P2251 indicates an issue with the negative current control circuit of the upstream oxygen sensor on bank 1.

How do I fix P2251?

Fixes include replacing damaged wiring/connectors, installing a new oxygen sensor, or replacing the PCM if it is faulty.

View source

Not affiliated with OBD2. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.

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