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Top 5 Reasons Your Engine Light Might Be On (And What To Do Next)
There’s nothing quite like the sinking feeling of seeing the engine warning light illuminate on your dashboard. While it’s tempting to ignore it—especially if the car feels fine—this little light can signal anything from a minor issue to something more serious.
At Cromwell Garage, we see this all the time. Here are the top 5 reasons your engine light might come on—and why it’s worth getting it checked sooner rather than later.
Faulty Oxygen Sensor (O2 Sensor)
The oxygen sensor measures how much oxygen is in your exhaust and helps your engine burn fuel efficiently. A faulty O2 sensor:
- Reduces fuel economy
- Increases emissions
- Can damage your catalytic converter if left unfixed
Fix: Requires diagnostic testing and sensor replacement. It's a common issue we handle quickly at our garage.
02
Loose or Damaged Fuel Cap
Yes — something as simple as a loose petrol cap can trigger your engine light! If it’s not sealing properly, fuel vapours can leak out, disrupting the fuel system.
Fix: Try tightening the cap and see if the light clears after a few drives. If not, pop in and we’ll inspect it for cracks.
03
Catalytic Converter Problems
Your catalytic converter helps reduce harmful emissions. If it's failing, you may notice:
- Poor acceleration
- Rotten egg smell
- Decreased fuel economy
04
Faulty Mass Airflow Sensor (MAF)
This sensor measures the amount of air entering the engine to determine how much fuel is needed. A faulty MAF sensor can cause rough idling, poor performance, or stalling.
Don’t delay: Driving too long in this condition can damage spark plugs or the catalytic converter.
05
Worn Spark Plugs or Ignition Coils
If your engine is misfiring, it could be due to worn spark plugs or faulty ignition coils. This can lead to poor fuel economy and increased emissions.
You might notice: Shaking, sluggish acceleration, or trouble starting the car.
What Should You Do If Your Engine Light Comes On?
Don’t panic. If the light is steady and the car drives normally, it’s usually safe to continue—but get it checked soon.
If it’s flashing, stop driving. A flashing engine light often means a serious misfire, which could damage your catalytic converter.
Book a diagnostic check. At Cromwell Garage, we use advanced diagnostics to pinpoint the issue and get you safely back on the road.
Serving Allesley, Balsall Common, Berkswell, Burton Green, Canley, Coundon , Cheylesmore, Earlsdon, Eastern Green, Finham, Kenilworth, Meriden, Tile Hill, Westwood Heath.
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