Fault code P0158 – a step-by-step guide to diagnosing and fixing it

Error code P0158 is displayed and the check engine light is on - what does this mean?

The OBD/EOBD system has detected that the voltage of the rear lambda sensor (bank 2, sensor 2) is too high. This DTC P0158 indicates a problem with the oxygen sensor after the catalytic converter, which is responsible for monitoring the exhaust gas purification.

What causes can this error code have?

• Defective rear lambda sensor (bank 2, sensor 2)
• Damaged cable connections to the lambda sensor
• Corroded or loose plug connections
• Short circuit in the wiring to the sensor
• Defective engine control unit (rare)
• Contamination of the lambda sensor by fuel additives
• Mechanical damage to the sensor due to heat or vibration
• Faulty earth connection

What symptoms occur in parallel with fault code P0158?

• Increased fuel consumption: The vehicle consumes more fuel than usual because the mixture control is impaired.
• Unsteady idling: The engine runs unevenly at idle or fluctuates in speed.
• Reduced engine power: Noticeable loss of power, especially at higher engine speeds.
• Exhaust problems: Increased pollutant levels and possible failure to pass the emissions test.
• Check engine light: The yellow warning light is permanently illuminated on the dashboard.

How can the problem with error code P0158 be rectified?

• Repairing trouble code P0158 requires a systematic approach to identifying and eliminating the cause.
• Replace the lambda sensor: Replace the defective rear lambda sensor (bank 2, sensor 2) with an original part or high-quality replacement part, as this is the most common cause of trouble code P0158.
• Check and repair the wiring: Check all cable connections to the lambda sensor for damage, corrosion or short circuits and repair or replace defective cables.
• Clean plug connections: Disconnect the plug connection to the lambda sensor, clean the contacts with contact spray and ensure a firm connection.
• Check the ground connection: Check the ground connections of the engine system and clean or replace corroded ground points.
• Clear fault memory and test drive: After the repair, clear the DTC with an OBD scanner and carry out an extensive test drive to check whether the fault code occurs again.