What does ECU stand for?

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Will Nightingale
10 January 2008

Q: In your used car review of the Ford Galaxy, you mention that it can suffer from ECU problems. Please can you tell me what 'ECU' stands for?
Steve Craddock

A: ECU stands for Engine Control Unit. It's also sometimes called the engine management system and is a small electronic box that monitors and optimizes the operation and performance of your engine.

ECUs in less-sophisticated cars simply control the amount of fuel injected into each cylinder. However, in many modern, more-advanced cars, it also controls the ignition timing and the level of boost provided by the turbocharger (if fitted).

Sophisticated braking and traction aids may also be linked to the ECU so that it can coordinate their operation with that of the engine.

Before ECUs were fitted to cars, a carburettor controlled the quantity of fuel entering the cylinders. The level had to be set manually, and often required adjustment at service intervals.

Replacement ECUs can be expensive, so it's worth thinking about the potential price of a replacement if you're considering buying a used Galaxy.

The cost will vary depending on the exact model of Galaxy, but expect to pay around 600 plus labour charges.