My garage says the ECU has failed. What now?
Told your ECU has failed? Check before you buy a new one
The short answer
An ECU (engine control unit) or other module can fail, but it is also often blamed for faults elsewhere: other modules report “no communication” when the real problem is wiring, a fuse box or a power supply. When the unit itself is faulty, failures from water ingress, corrosion or a burnt component can often be repaired, which keeps the original coding and immobiliser data.
Common real causes
- Water or coolant leaking onto or into the unit
- Corroded connectors, fuse boxes or earth points
- Wiring damage, including chafed looms and rodent damage
- Previous repair or tuning attempts that went wrong
What to do now
- Ask what testing showed the unit, rather than its wiring, to be at fault.
- Ring us with the vehicle and the fault codes.
- Garages can send the unit on its own for testing.
Draft Technical wording to be reviewed by PK before publishing.