Vehicle diagnostic check: what is that warning light?
A dashboard warning light is worrying. A diagnostic check reads the fault code, tells you what it means and what it will take to fix, before a small problem becomes a big bill.
What a diagnostic check is
Most modern cars have an on-board computer that watches performance all the time. When a sensor reports a problem, such as low fluid or a high engine temperature, the computer stores an error code and lights the matching warning. There are hundreds of possible codes, and they can only be read with specialist equipment.
A check can point to problems with the engine, brakes, exhaust and other major components, as well as performance faults such as air flow or throttle, and failed sensors.
When to get one
- A warning light
- It could be something trivial, like a loose fuel cap, or serious. The check finds out which.
- Something feels off
- An odd smell or noise, even with no light on.
- Once a year
- As part of routine care, to catch small faults early.
- Before buying a used car
- Peace of mind to go with the service history.
A warning light has come on. What should I do?
Have it checked as soon as you can. Even a warning that looks minor is worth expert advice, in case the cause is more serious. If the light is red, or the car is running badly, stop somewhere safe and call us.