P0605 Fault Code in Land Rover: Causes, Symptoms, and Fixes

The ECU/PCM/TCM continuously checks its internal memory integrity. ROM (Read Only Memory) stores the permanent software/programming that runs the module. If this memory gets corrupted or fails validation, the module triggers P0605. This is more severe than P0603 (KAM) or P0604 (RAM), since it points to a potential permanent hardware or software corruption.

Common Causes:

1. ECU/PCM/TCM software corruption
2. Failed or incomplete module reprogramming/update
3. Voltage spikes from battery/alternator issues
4. Water or heat damage to ECU/TCM
5. Actual control module failure

Symptoms:

1. Check Engine Light (CEL)
2. Engine may not start or may stall randomly
3. Harsh or erratic shifting (if TCM affected)
4. Limp mode activation
5. Poor performance, rough idle, hesitation
6. In some cases → no communication with scanner

Fixes:

1. Check battery/alternator health – prevent voltage spikes.
2. Inspect module wiring/connectors – corrosion, poor grounds, loose terminals.
3. Attempt ECU/TCM reflash or reprogramming with factory software.
4. If software reload fails → replace ECU/PCM/TCM (ROM failure is usually permanent).