Engine-CodesMercury – P2251 Mercury

P2251 Mercury Code - O2 Sensor Negative Current Control Circuit Open Bank 1 Sensor 1

Quick Answer

The P2251 code for Mercury vehicles specifically indicates an issue with the O2 sensor negative current control circuit on Bank 1 Sensor 1. Common causes include Corroded or damaged wiring in the O2 sensor circuit, Faulty O2 sensor, Loose or poor connection in the O2 sensor circuit. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

What it means
P2251 Mercury indicates O2 Sensor Negative Current Control Circuit Open Bank 1 Sensor 1.
Common causes
Common causes include Corroded or damaged wiring in the O2 sensor circuit, Faulty O2 sensor, Loose or poor connection in the O2 sensor circuit.
Severity
Moderate - service should be scheduled soon.
Can I drive?
The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.
Table of contents Created and updated by William Orellana on Sep 09, 2024
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Code P2251 Mercury Description

The P2251 code for Mercury vehicles specifically indicates an issue with the O2 sensor negative current control circuit on Bank 1 Sensor 1. This sensor is responsible for monitoring the oxygen levels in the exhaust gases and sending this data to the engine control module (ECM) for proper air/fuel ratio adjustments. When the ECM detects an open circuit in the negative current control circuit of the O2 sensor, it triggers the P2251 code.

OBDII Code P2251 Mercury - O2 Sensor Negative Current Control Circuit Open Bank 1 Sensor 1
P2251 Mercury Code - O2 Sensor Negative Current Control Circuit Open Bank 1 Sensor 1

Common Causes of P2251 Mercury

  1. Corroded or damaged wiring in the O2 sensor circuit
  2. Faulty O2 sensor
  3. Loose or poor connection in the O2 sensor circuit
  4. Issues with the ECM
  5. Exhaust leaks near the O2 sensor

Symptoms of P2251 Mercury

  1. Decreased fuel efficiency
  2. Engine misfires
  3. Rough idling or stalling
  4. Illuminated check engine light
  5. Poor acceleration

How to Fix P2251 Mercury

  1. Begin by performing a visual inspection of the O2 sensor wiring and connectors to check for any signs of damage or corrosion.
  2. Use a multimeter to test the continuity of the wiring in the O2 sensor's negative current control circuit.
  3. Replace the O2 sensor if it is found to be faulty or damaged.
  4. Repair any damaged wiring or connectors in the O2 sensor circuit.
  5. Clear the error codes from the vehicle's ECM and perform a test drive to ensure the issue has been resolved.

Cost to Fix P2251 Mercury

The typical repair costs for addressing the P2251 code can range from $200 to $500, depending on the specific cause of the issue and the cost of parts and labor. It's important to note that diagnostic time and labor rates at auto repair shops can vary, with hourly rates typically ranging between $80 to $150. Additional costs may apply if other components need to be replaced or repaired. It's recommended to consult with a professional mechanic for a more accurate estimate based on the specific vehicle make and model.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

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