Dashboard Warning Lights
What Is the Check Engine Light?
A knocking or clunking noise when driving over speed bumps, potholes, or rough ground is one of the most common suspension complaints. The sound usually comes from underneath the car and can range from a soft thud to a loud clunk or knock. It may happen every time you go over a bump, or only on sharper impacts.
Some drivers also notice the steering feeling loose or vague, the car bouncing more than usual after a bump, or a rattling sound on uneven roads. These are all signs that something in the suspension or steering system needs attention.
Solid Check Engine Light
A solid, steady check engine light means that a fault has been detected but it is not considered an immediate emergency. The car’s system has logged an error code and is telling you that something needs looking at, but you can usually continue driving carefully in the short term.
Common causes of a solid check engine light include a loose or faulty fuel cap, a worn oxygen sensor, a failing catalytic converter, or issues with the fuel or ignition system. These are not things to ignore, but they are unlikely to cause sudden damage if addressed within a day or two.
Flashing Check Engine Light
A flashing check engine light is a much more serious warning. It means the fault is active right now and is severe enough to cause damage if you keep driving. In most cases, a flashing light indicates an engine misfire, where fuel is not being burned correctly in one or more cylinders. Unburned fuel can overheat and damage the catalytic converter within minutes, turning a manageable repair into a far more expensive one.
If your check engine light is flashing, you should stop driving as soon as it is safe to do so.
What Could Be Causing It?
There are many possible causes, ranging from minor to serious. Only a car diagnostics check can read the fault codes stored in your car’s system and tell you exactly what is wrong.
Loose or Faulty Fuel Cap
One of the simplest causes of a solid check engine light is a loose, damaged, or missing fuel cap. The fuel system is sealed, and if the cap does not create a proper seal, the system detects a pressure loss and triggers the light. Tightening or replacing the cap may clear the light after a few drive cycles.
Oxygen Sensor Fault
Oxygen sensors measure how much unburned oxygen is in the exhaust and help the engine management system balance the fuel mixture. A faulty sensor can cause poor fuel economy and higher emissions, and will trigger the check engine light.
Engine Misfire
An engine misfire happens when one or more cylinders fail to fire correctly. This can be caused by worn spark plugs, faulty ignition coils, a blocked fuel injector, or low compression. A misfire is the most common cause of a flashing check engine light and can cause serious damage quickly.
Catalytic Converter Issues
The catalytic converter reduces harmful emissions from the exhaust. If it becomes blocked or damaged, often as a result of a long-running misfire, it will trigger the check engine light. A failed catalytic converter will also cause your car to fail an MOT test.
Mass Airflow Sensor Fault
The mass airflow sensor measures how much air is entering the engine so the system can deliver the right amount of fuel. If it fails or becomes dirty, the engine may run roughly, use more fuel, or struggle to start.
EGR Valve Issues
The exhaust gas recirculation (EGR) valve helps reduce emissions by redirecting some exhaust gases back into the engine. If it sticks open or closed, it can cause poor performance and trigger the warning light.
Spark Plugs or Ignition Coils
Worn spark plugs or failing ignition coils are very common causes of engine misfires and check engine lights, especially on older cars. These are relatively affordable to replace but should not be left too long.
Dashboard Warning Lights
Is It Safe to Drive?
| What you are experiencing | Is it safe to drive? | What to do |
|---|---|---|
| Solid check engine light, car driving normally | Use caution | Book a diagnostics check within 1 to 2 days. Do not ignore it. |
| Solid check engine light with rough running or poor performance | Not recommended | Have it checked as soon as possible. The fault may be getting worse. |
| Flashing check engine light | Do not drive | Stop safely as soon as you can. Continuing to drive risks serious engine damage. |
| Flashing check engine light plus unusual smells or sounds | Do not drive | Call us immediately or arrange recovery. |
| Check engine light plus temperature warning light | Do not drive | Could indicate multiple faults. Stop and call for assistance. |
| Check engine light plus oil warning light | Do not drive | Serious risk of engine damage. Stop immediately and call for recovery. |
Dashboard Warning Lights
What Should You Do?
1. Note whether the light is flashing or solid. This is the most important thing to check. A flashing light means stop as soon as it is safe. A solid light means book a check promptly but you can usually drive carefully in the short term.
2. Check the fuel cap. If the light is solid and the car seems to be running normally, check that your fuel cap is fully tightened. If it was loose, the light may clear itself after a few trips once the system resets.
3. Do not ignore it and hope it goes away. The check engine light will not turn itself off unless the fault is resolved. Driving with an undiagnosed fault risks further damage and a more expensive repair.
4. Call First Auto Centre. Give us a call on 020 4539 0131 and tell us whether the light is flashing or solid and how the car is driving. Our team can advise you straight away and get you booked in for a car diagnostics check at our East Ham garage.
5. Get the fault codes read. The only reliable way to find out what is causing the light is to plug a diagnostics tool into the car’s onboard computer. This reads the stored fault codes and gives our mechanics a clear starting point for the inspection and repair.
Check Engine Light On?
Let Us Take a Look.
Whether it is flashing or solid, the check engine light is your car telling you something is wrong. At First Auto Centre in East Ham, our car diagnostics service will read your fault codes, identify the cause, and give you a clear and honest explanation of what needs to be done.
Call us on 020 4539 0131 or visit us at 1 Lawrence Road, East Ham, London, E6 1JN.
We are open Monday to Saturday, 09:00 to 18:00.
This page is for general guidance only. Only a diagnostics check and physical inspection can properly identify the cause of a check engine light. If your light is flashing, stop driving and call us.
Transparent & Honest Advice
No unnecessary repairs or hidden fees—just straightforward, honest assessments.
Your Questions
FAQs
No. If the check engine light is illuminated during an MOT test, the car will automatically fail. The light indicates a stored fault, and faults in the engine management system are assessed as part of the test. You should get the fault diagnosed and fixed before booking your MOT.
Sometimes. If the fault was minor and temporary, such as a loose fuel cap that has since been tightened, the light may clear itself after several drive cycles. However, if the underlying fault is still present, the light will stay on or come back. Do not assume it has fixed itself without getting it checked.
A diagnostics check at First Auto Centre is usually quick. Reading the fault codes from the car's system only takes a few minutes. The time required for any resulting repairs depends on what the codes reveal.
No. A service light is a reminder that your car is due for routine car servicing, such as an oil change or filter replacement. A check engine light indicates a specific fault in the engine management system. They look different and mean very different things.
This is often caused by a loose fuel cap. The fuel system needs to be sealed, and if the cap was not fully tightened after filling up, the system detects a leak in the evaporative emissions system and triggers the light. Tighten the cap and see if the light clears after a few journeys.
We would not recommend it. While a solid check engine light is not always an immediate emergency, motorway driving puts more sustained load on the engine. If the fault worsens while driving at speed, it could become dangerous. Get the fault checked before making longer journeys.
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Contact Us
- info@firstautocentre.co.uk
- 1 Lawrence Road, Newham, London, E6 1JN
- Mon-Sat: 09:00 - 18:00
- Sunday: Closed
