Error code P1605 is displayed and the check engine light is on - what does this mean?
The DTC P1605 is a manufacturer-specific fault code that is recognized by the OBD system and indicates a problem with the engine control unit (PCM/ECM). This trouble code occurs when the EOBD system detects a fault in the internal communication or processing of the control unit. Depending on the vehicle manufacturer, the exact definition of fault code P1605 may vary, but typically refers to internal PCM errors or memory problems.
What can cause this fault code?
- Defective engine control unit (PCM/ECM)
- Corrupt software or firmware in the control unit
- Voltage problems in the power supply of the PCM
- Damaged internal memory modules
- Overheating of the engine control unit
- Electromagnetic interference
- Faulty ground connections to the control unit
- Defective internal processors or circuits
What symptoms occur in parallel with fault code P1605?
- Starting problems: The vehicle is difficult or impossible to start
- Engine misfires: Irregular engine running and jerky driving
- Loss of power: Reduced engine power and poor acceleration
- Emergency running program: Engine only runs in emergency mode with limited power
- Electronic problems: Failure of various control unit functions
- Irregular idling: Engine runs unevenly at idle speed
- Complete engine failure: In severe cases, the engine no longer starts
How to fix the problem of error code P1605?
- Repairing the P1605 usually requires professional diagnosis, as the problem is internal to the control unit.
- Carry out a control unit reset: Disconnect battery for 30 minutes and allow all capacitors to discharge, then reinitialize control unit
- Install software update: Have the latest firmware for the PCM installed by the authorized dealer
- Check the power supply: Check all fuses, relays and cable connections to the engine control unit and replace defective parts
- Clean earth connections: Clean and tighten all ground points on the control unit
- Replace the engine control unit: In the event of irreparable internal damage, replace the entire PCM with an original spare part and have it programmed
- Professional diagnosis: Visit a specialized workshop with manufacturer-specific diagnostic equipment
FAQ - Frequently asked questions about DTC P1605
Can I continue driving with error code P1605?
Continuing to drive with code P1605 is not recommended, as this is a critical control unit error. The vehicle can fail completely or switch to emergency mode at any time.
How much does it cost to repair error code P1605?
The costs for P1605 vary greatly: software updates cost €100-200, while an ECU replacement can cost €800-2500. A precise diagnosis usually costs €100-150.
Can error code P1605 be caused by a battery change?
Yes, P1605 can occur after a battery change if the control unit has not been reset properly. Reprogramming the PCM usually helps.
Is the DTC P1605 the same for all manufacturers?
No, P1605 is a manufacturer-specific trouble code. It means something different for BMW than for Ford or other brands. The exact definition must be checked on a manufacturer-specific basis.
Can I delete fault code P1605 myself?
It is possible to delete it with an OBD scanner, but this does not eliminate the cause. The fault code will usually reappear immediately if the underlying problem has not been rectified.
How long does it take to repair P1605?
Depending on the cause, the repair takes 1-8 hours. A software update takes 1-2 hours, while an ECU replacement can take a whole working day.