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Engine Diagnostics

Have you got a warning light on your vehicle dashboard?

Warning lights are designed to alert you to potential issues and if they stay on or illuminate whilst you’re driving there’s a cause for concern. 

The warning light you see on your dashboard only gives you a very small part of the picture. Professional diagnostics read the error messages that cause the light to illuminate, identifying the root cause. An early diagnostic check is strongly recommended to help prevent component failures which can lead to further damage and expensive repairs.

Vehicle fault codes

Modern vehicles are crammed full of electronic features & technology. In order to check the electronics are working as they should, they are fitted with sensors to help monitor their condition. These sensors continually report to the ECU (Engine Control Unit) and if a problem occurs, it logs a fault code on the ECU’s memory. If the ECU detects an issue, you’ll be alerted to it by a warning light on your dashboard. 

The warning lights on your dashboard follow a traffic light colour system:

Yellow or Amber lights advise the driver that something isn’t working as it should be. You should take extra care and get a professional diagnostic check as soon as possible

Red lights indicate a more serious & potentially dangerous problem. You should stop driving as soon as it is safe to do so.

If a warning light or fault code appears on your dashboard we’d advise you to contact your local branch to book a diagnostic health check. Whilst it may be something very minor, warning lights could also indicate a more serious problem. It may be tempting to delay booking your vehicle into the workshops but the earlier we can investigate the issue, the less likely it will be that damage is done.


What problems does the ECU pick up?

The ECU can pick up problems with emission levels, engine temperatures and even windscreen wipers. You may see a warning light on your dashboard, but this only gives you a very small part of the picture. Our diagnostic health checks read these error messages and identify the root cause, so component failures can be prevented before they lead to further damage and expensive repairs.

What is a diagnostic health check?

A diagnostic health check is carried out by a trained vehicle technician using specialist diagnostic equipment. This equipment is designed to read fault codes and clear error codes.  In order to be able to read as many codes as possible, we carry a range of diagnostic equipment across our branches. Using different systems gives us a much wider coverage than most other independent garages.

The cost of our diagnostics is fixed at £39.95 in all our branches. If we discover problems with your engine or other components we’ll then provide you with a free, no-obligation repair quote.

A guide to dashboard warning lights

Engine Management Light
Temperature warning light
TPMS light
Air-Bag Light
Battery light
Brake Warning Light

FAQ's about dashboard warning lights

What should I do if my engine management light is on?

Your engine management light is an engine shaped light that comes on when the ECU detects there’s an engine related fault.

The colour of the light can help to tell you how serious the issue is. If the light is yellow or orange this shows your vehicle has a fault which should be checked by booking an engine diagnostic health check. If this is the case, don’t panic but do pay attention to how your car feels and sounds which may help you know how serious the issue is. You can usually continue on your journey (as long as it’s not too far) and make plans to get it checked as soon as possible.

If the orange light is flashing or is red this indicates a more serious problem that needs investigating immediately. You should pull over as soon as it’s safe to do so and arrange to have your car recovered to a garage. A red or orange flashing engine light indicates a dangerous fault that shouldn’t be ignored.

What should I do if my airbag light is on?

The airbag light shows a seated passenger with a circle above them.  If this light is on it indicates there’s an issue with your airbag or seatbelt. As both of these are vital for driver and passenger safety it’s important you get this fault checked as soon as possible.

What should I do if my temperature warning light comes on?

Your engine temperature warning light looks like a thermometer submerged in liquid. If this light comes on it means your on-board computer has detected that your coolant temperature is too high, a warning that your engine is overheating. If this happens, pull your vehicle over and switch off the engine where it’s safe to do so. This fault requires immediate attention as continuing to drive a vehicle with an overheated engine could cause permanent engine damage.

What should I do if my TPMS light is on?

If your TPMS light is on it indicates at least one of your tyres doesn’t have enough pressure and therefore could be unsafe. An underinflated tyre could simply need the pressure checking and resetting, or could be caused by a puncture. If your TPMS is on call into a garage for a tyre pressure check as soon as possible.

What should I do if my ABS light is on?

Your ABS light comes on when there is a problem with your anti-lock braking system. This is the technology that helps prevent your wheels from locking up under harsh braking, limiting the chances of your vehicle skidding.  If this light comes on your normal brakes will still work, so the general advice is that you can continue driving with extra care and caution. It’s advised to book your car in to get this looked at as soon as possible. It could be caused by low brake fluid levels or loss of pressure in the braking system.

What should I do if my oil light comes on?

Your oil light coming on could indicate a number of issues, The most common cause of the oil light warning is low engine oil or oil, worn out oil. However, this light could also alert you to a faulty oil pressure gauge or oil pump, a clogged filter or over-heated engine. As oil lubrication is essential for your engine it’s important to check your oil level and get this light checked urgently to avoid damage.

What does a red dashboard light mean?

A red dashboard light indicates a serious problem and you should stop driving the car as soon as it’s safe to pull over. With a red warning light we’d advise you get the car recovered to a garage for diagnostics and repair.

What does a yellow dashboard warning light mean?

A yellow warning light tells you there is a fault but it’s not too serious or dangerous. If you have a yellow warning light you can continue driving your vehicle but get the fault looked at as soon as possible. 

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