Put the Wrong Fuel in Your Car? Do This Immediately

It happens more often than you’d think. You pull into the petrol station, reach for the pump on autopilot, and only realise what you’ve done when the nozzle is in the tank. Maybe you’ve switched to a diesel car after years of driving petrol. Maybe you were distracted. Maybe you were just tired.

Whatever the reason, the key thing to know is: don’t panic, and above all — do not start the engine.

Why Misfuelling Is Serious

The two most common misfuelling errors are putting petrol into a diesel car, or putting diesel into a petrol car. Each has different consequences.

Petrol in a diesel engine is the more serious of the two and by far the more common. Petrol acts as a solvent in a diesel system. It strips the lubrication from the fuel pump and injectors, causing metal-to-metal contact and potentially catastrophic damage if the engine is run. Modern diesel engines have high-pressure fuel systems (common rail) that are extremely sensitive — even a small amount of petrol contamination can be destructive.

Diesel in a petrol engine is less common and generally less damaging. Diesel is thicker and harder to ignite in a petrol engine, which may cause misfires, excessive smoke and rough running. The car may struggle to start or cut out, but the damage is usually less severe — though a full drain is still necessary.

The Critical Rule: Don’t Start the Engine

If you’ve put the wrong fuel in and haven’t started the engine, you’ve saved yourself potentially thousands of pounds in damage. The contaminated fuel is sitting in the tank and hasn’t yet circulated through the fuel system.

Move the car to a safe location if you can push it without starting it, or if you’re at a busy pump, tell the forecourt staff and they’ll help you get it moved.

Call a specialist fuel drain service immediately.

What Happens If You’ve Already Started It?

If you started the engine and drove even a short distance, there’s a chance the contaminated fuel has begun circulating. Turn the engine off immediately and don’t restart it. The longer it runs, the more damage accumulates.

At this point you still need a fuel drain, but you may also have pump and injector damage that will need assessment. A good recovery and fuel drain service will be honest with you about what they find.

How Fuel Drain and Rescue Works

A specialist fuel drain technician will:

1. Remove the contaminated fuel from the tank using specialist equipment

2. Flush the fuel system (including lines and filter) with the correct fuel

3. Refill with the correct fuel

4. Carry out a start and run test

In most cases where the engine wasn’t started, this process gets you back on the road within an hour. If there’s system damage, the vehicle will need to go to a garage for further work.

Cost of Wrong Fuel Recovery

A fuel drain service typically costs £150–£300 depending on location and tank size. This sounds significant, but it’s a fraction of the cost of a replacement fuel pump (£400–£1,500) or full injector set (£1,000–£3,000+).

More importantly, the cost only rises if you start the engine and wait. Every minute it runs on the wrong fuel increases the repair bill.

Call Jam’s Recovery for Wrong Fuel Assistance

If you’ve misfuelled in or around Milton Keynes, Northampton, Bedford or surrounding areas, call 07369 205 703 immediately. We’ll advise you exactly what to do and get a specialist to you as quickly as possible.

The important thing is speed — call as soon as you realise what’s happened.

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*Jam’s Breakdown & Recovery operates 24/7 across the Milton Keynes area. Call 07369 205 703 for fast roadside assistance including wrong fuel recovery.*