Fault code P0159 – a step-by-step guide to diagnosing and fixing it

Error code P0159 is displayed and the check engine light is on - what does this mean?

DTC P0159 is triggered by the OBD system if lambda sensor 2 in bank 2 (downstream of the catalytic converter) reacts too slowly to changes in the air/fuel mixture. This EOBD error code indicates a slow response time of the oxygen sensor, which is responsible for monitoring the catalytic converter efficiency.

What can cause this fault code?

• Defective lambda sensor 2 in bank 2
• Contamination of the oxygen sensor due to oil residue or additives
• Damaged or corroded cable to the lambda sensor
• Loose or oxidized plug connections
• Defective catalytic converter with reduced efficiency
• Leak in the exhaust system downstream of the catalytic converter
• Faulty ground connection of the lambda sensor
• Wear of the sensor heater

What symptoms occur in parallel with fault code P0159?

• Increased fuel consumption: The vehicle consumes more fuel than usual
• Uneven engine running: The engine runs unevenly, especially when idling
• Reduced engine power: Noticeable loss of power when accelerating
• Exhaust odor: Unusual smell from the exhaust
• Jerking when driving: Irregularities while driving
• Increased exhaust values: Deteriorated emission values during the emissions test

How can the problem with error code P0159 be rectified?

• The repair requires a systematic diagnosis to identify the exact cause.
• Replacement of the defective lambda sensor 2 in bank 2 with an original part or a high-quality spare part
• Cleaning the lambda sensor with a special cleaner and checking its function
• Repair or replace damaged cables and plug connections to the oxygen sensor
• Checking and repairing the ground connection of the lambda sensor to the engine block
• Replacing the catalytic converter if it is proven to be inoperable
• Sealing of leaks in the exhaust system using welding work or sealant
• Checking and replacing the sensor heater if the heating function is defective