P2251 Fault Code

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

• What does that mean?
• Symptoms
• Causes
• Solutions

The P2251 fault code indicates an issue with the oxygen (O2) sensor's negative current control circuit or an open circuit on Bank 1 Sensor 1.

• This sensor plays a critical role in managing the air-fuel mixture by monitoring the level of oxygen in the exhaust gases.
• A malfunction can lead to poor engine performance, increased emissions, and lower fuel efficiency.

What are the symptoms of the P2251 code?

Common symptoms associated with the P2251 fault code include:

• Illuminated check engine light.
• Decreased fuel efficiency.
• Engine hesitations or misfires.
• Rough idling or stalling.
• Increased emissions of pollutants.

What causes the P2251 code?

The fault can be caused by several factors including:

• A defective O2 sensor.
• Damaged wiring or connectors in the sensor circuit.
• A blown fuse affecting the sensor circuit.
• Issues with the engine control unit (ECU) that affect sensor performance.

How to fix P2251?

To resolve the P2251 fault code, follow these steps:

• Start by scanning the vehicle’s computer with an OBD-II scanner to confirm the code.
• Inspect the O2 sensor and its wiring harness for any signs of damage.
• Test the O2 sensor for proper operation using a multimeter.
• If necessary, replace the faulty O2 sensor and repair any damaged wiring.
• Clear the fault codes and take the car for a test drive to ensure the problem is resolved.