6 Signs to Pay Attention to That Indicates Misfuelling

misfuelling diesel car

Misfuelling, or accidentally filling your diesel car with petrol, is a surprisingly common mistake that can cause significant damage to your vehicle’s engine. Diesel and petrol engines are designed to operate differently, and using the wrong fuel can lead to a range of issues.

In this article, we will discuss several symptoms of misfuelling your diesel car with petrol, so you can identify the problem and take action before it’s too late:

1. Difficulty Starting the Engine

One of the first symptoms of misfuelling is difficulty starting the engine. Petrol acts as a solvent in a diesel engine, which can reduce the lubrication provided by the diesel fuel and cause damage to the fuel system components. As a result, the engine may struggle to start or may not start at all. If you’ve recently filled up your diesel car and are experiencing trouble starting, consider the possibility of misfuelling.

2. Engine Stalling or Cutting Out

If you manage to start your diesel car after misfuelling, you may notice the engine stalling or cutting out while driving. This is because petrol is less dense and more volatile than diesel, which can cause the engine to misfire and shut down. If your car suddenly stops running and you suspect misfuelling, do not attempt to restart the engine, as this can cause further damage.

3. Unusual Noises from the Engine

Misfuelling can cause unusual noises to emanate from your diesel engine, such as knocking, pinging, or rattling sounds. This is due to the reduced lubrication and increased friction within the engine. When petrol comes into contact with diesel engine components, it can cause them to wear faster, leading to these abnormal noises.

4. Poor Performance and Reduced Fuel Efficiency

A diesel engine running on petrol will experience reduced performance and fuel efficiency. The engine may struggle to accelerate, and you may notice a decrease in overall power. Additionally, the engine may consume more fuel than usual as it attempts to compensate for the lack of lubrication and the increased volatility of the petrol.

5. Excessive Smoke from the Exhaust

One of the most noticeable symptoms of misfuelling is excessive smoke coming from the exhaust. When petrol is burned in a diesel engine, it produces a higher amount of unburned hydrocarbons, which can cause thick, black smoke to billow from the exhaust. This is not only harmful to the environment but can also be a telltale sign that something is wrong with your vehicle.

6. Check Engine Light or Warning Messages

Finally, modern diesel cars are equipped with sophisticated engine management systems that can detect misfuelling. If your car’s system detects that petrol has been added to the fuel tank, it may trigger a check engine light or a warning message on the dashboard. While these warnings can indicate a variety of issues, they should never be ignored, especially if you suspect misfuelling.


If you experience any of the symptoms listed above after filling up your diesel car, it’s crucial to act quickly to minimise the damage. Do not attempt to drive the vehicle or start the engine, as this can cause further harm. Instead, contact a professional mechanic or roadside assistance service to help drain the petrol from your fuel system and assess any potential damage!

Are you in a predicament with your wrongly-fueled vehicle? We’re here for you! Fuel Fixer offers mobile units across the UK to help with wrong fuel issues. If you’ve put the wrong fuel in your vehicle, contact us right away and get the issue solved quickly!

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