Fault code P0605 – a step-by-step guide to diagnosing and fixing it

Error code P0605 is displayed and the check engine light is on - what does this mean?

The DTC P0605 indicates a critical error in the internal ROM (Read-Only Memory) of the engine control unit, which the OBD system has detected. This fault code indicates damage or corruption of the firmware in the ECM/PCM, which can lead to serious engine problems.

What can cause this fault code?

• Corrupt or damaged ECM/PCM firmware
• Defective engine control unit (ECM/PCM)
• Voltage spikes or electrical overload
• Faulty software updates or programming
• Memory errors in the ROM due to ageing
• Water damage to the control unit
• Overheating of the engine control unit

What symptoms occur in parallel with error code P0605?

• Starting problems: The vehicle is difficult or impossible to start
• Engine misfires: Irregular engine running and jerky movements
• Loss of power: Significantly reduced engine power while driving
• Stalling: Engine stalls while driving or idling
• Emergency running program: Vehicle switches to safety mode with limited power
• Shifting problems: Shifting errors can occur with automatic transmissions

How can the problem with error code P0605 be rectified?

• Repairing trouble code P0605 usually requires professional help, as it is a critical ECU error.
• ECM/PCM reprogramming: Have the engine control unit reprogrammed and calibrated by a specialist workshop using the latest software
• ECU replacement: In the event of irreparable damage, the entire ECM/PCM must be replaced with a new or reconditioned unit and then programmed
• Electrical check: Check all power supply lines and earth connections to the control unit for corrosion or loose contacts
• Fuse check: Check all relevant fuses and relays of the engine control unit and replace defective components
• Voltage stabilization: Have the alternator and battery checked to avoid future voltage spikes that could damage the control unit