Engine Diagnostics

We’re asked this every day, and there’s no single answer. The light comes on when your car’s ECU (engine control unit) detects a fault. The fault is picked up by the electrical system, but it can also be caused by mechanical failures. Modern cars are packed with sensors that monitor your engine from start to finish. Once a sensor detects a problem, the ECU lights up the EML (engine management light) on the dashboard to warn you.

When we say cars are packed with sensors, we mean it. There are literally thousands of reasons you might see that light. Here are some of the most common ones we see at Childwall Fiveways Auto Centre:

• Turbo failure: your car often knows a turbo has failed before you do, as it can detect changes in emissions or pressure in the exhaust.
• Blown fuse: a lot of the car runs through electrical sensors, so a blown fuse can quickly lead to errors being reported to the ECU.
• Your car needs a service: skipping services can bring the EML on. As your air and oil filters clog up, the emissions your car produces change, and the sensors report this as a fault.
• Failed battery: usually a winter fault. If your battery isn’t charging, vital equipment doesn’t get enough power to run.