Fault code P0151 – a step-by-step guide to diagnosing and fixing it

Error code P0151 is displayed and the check engine light is on - what does this mean?

The OBD/EOBD system has detected too low a voltage at lambda sensor 2 in bank 1. This DTC P0151 indicates a problem with the downstream oxygen sensor, which monitors the efficiency of the catalytic converter. Slight variations in the diagnosis may occur with different manufacturers, but the basic problem remains the same.

What can cause this error code?

• Defective lambda sensor 2 (bank 1)
• Damaged or corroded cable connections to the sensor
• Loose or poor plug connections
• Short circuit in the sensor circuit
• Defective engine control unit (ECU)
• Damaged wiring harness due to heat or wear
• Incorrect sensor voltage due to electrical faults
• Defective ground wire of the sensor

Which symptoms occur in parallel with fault code P0151?

• Increased fuel consumption: The vehicle consumes more fuel than usual
• Poor exhaust values: Increased emission values during the emissions test
• Uneven idling: The engine runs unevenly at idle
• Loss of power: Reduced engine power, especially when accelerating
• Check engine light: Continuously lit or flashing warning light
• Jerking when driving: Uneven engine running while driving

How can the problem with error code P0151 be rectified?

• The repair requires a systematic diagnosis to identify the exact cause.
• Replace lambda sensor 2 in bank 1 completely, as this is usually the main cause of fault code P0151
• Check all cable connections and plug connections to the sensor, clean or replace if corroded
• Check the wiring harness between the sensor and control unit for damage and repair any defective sections
• Check the ground cable of the sensor and replace if contact is poor
• Diagnose engine control unit and replace or reprogram if defective
• Measure the electrical voltage in the sensor system and repair the power supply if there are deviations