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Symptom

Ran badly after filling up

The car was fine, you filled it, and within a few miles it was misfiring, lacking power or refusing to run cleanly. The timing is the diagnosis and it is worth stating first, because a fault that begins at a fuel pump points at the fuel rather than at the car — contaminated stock, water taken on with the delivery, the wrong grade, or on a diesel the wrong fuel entirely. Modern engines measure what they are burning and adapt, which is why the symptom often builds over the first few miles rather than arriving at once. Do not keep driving to see if it clears: high-pressure injection equipment is destroyed by water and by petrol in a diesel, and the damage is done in minutes.

Also described as: ran rough after fuel, problem started after filling up, bad fuel, misfiring after refuelling, contaminated fuel, wrong fuel, بعد از بنزین زدن بد شد, بنزین بی کیفیت زدم, va mal despues de repostar, eche gasolina y falla, empezo despues de cargar gasolina, despues de echar gasolina, بدأت المشكلة بعد تعبئة البنزين, بعد ما عبيت بنزين صارت تخربط, ساءت بعد التزود بالوقود

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Some causes mean you should stop driving

4 of the 29 codes that produce this symptom indicate a fault where continuing to drive risks damage or is unsafe. If the symptom is sudden or severe, treat it as one of those until a scan says otherwise.

What this usually means

The timing is the diagnosis and it is worth stating first. A fault that begins at a fuel pump points at the fuel rather than at the car — contaminated stock, water taken on with the delivery, the wrong grade, or on a diesel the wrong fuel entirely.

Modern engines measure what they are burning and adapt, which is why the symptom often builds over the first few miles rather than arriving at once. The management trims fuelling to keep the mixture right, runs out of authority, and only then does the car misfire or lose power — so an owner who filled up twenty minutes ago and is now on a motorway has a genuinely useful timeline to report.

Do not keep driving to see if it clears. High-pressure injection equipment is destroyed by water and by petrol in a diesel, and the damage is done in minutes — diesel is the pump's and the injectors' lubricant, so petrol in the tank does not dilute a lubricant, it removes one.

Draw a sample before anything else. Water separates and sits below the diesel, visibly. Petrol in diesel is harder to see and easier to smell. A sample costs nothing and settles a question that otherwise costs a fuel system.

Keep the receipt and note the station and pump. Contaminated stock affects more than one vehicle, and the supplier's records are the evidence that turns this from an expensive repair into a claim.

The innocent version exists too. Filling to the brim on a car with an evaporative system can produce a temporary fault and a check-engine light from liquid reaching the vapour canister — which is a lesson about the filling rather than the fuel.

Working through it

  • Misfire or power loss within a few miles of filling

    Likely cause
    The fuel — contaminated stock, water, or the wrong grade
    How to confirm it
    Draw a sample and look at it. Water separates below diesel and is visible; petrol in diesel is smelled rather than seen.
    What fixes it
    Drain and refill, renew the filter, and prime. Do not keep driving to see whether it clears.
  • Diesel filled with petrol, or the reverse

    Likely cause
    Wrong fuel — on a diesel this removes the injection system's lubrication rather than diluting it
    How to confirm it
    Establish it from the receipt and the sample. Do not run the engine to confirm; that is the damaging test.
    What fixes it
    Drain and flush professionally before starting. The further it has been driven, the larger the repair.
  • Water drained from the filter bowl, or a water warning lamp

    Likely cause
    Water taken on with the delivery, or condensate disturbed by the fill
    How to confirm it
    Drain the filter bowl and catch what comes out. This is free and takes minutes.
    What fixes it
    Drain the filter and, where the quantity is large, the tank. Renew the filter and prime.
  • Check-engine light shortly after brimming the tank, no driveability fault

    Likely cause
    The evaporative system — liquid fuel reaching the vapour canister after filling past the first cut-off
    How to confirm it
    Read the code; the evaporative family names itself. Note whether the tank was filled past the nozzle's first click.
    What fixes it
    Allow drive cycles to clear it, and stop filling past the first cut-off. The canister may need renewing if it has been soaked repeatedly.
  • Symptom built gradually over the first few miles

    Likely cause
    The management adapting and then running out of authority — consistent with a fuel quality problem rather than a mechanical one
    How to confirm it
    Read fuel trims and any injector correction values. The build-up pattern is itself evidence of the timeline.
    What fixes it
    Treat as a fuel problem. Trims return once the correct fuel is in and the system has relearned.
  • Other drivers report the same from the same station

    Likely cause
    Contaminated stock rather than anything about this vehicle
    How to confirm it
    Keep the receipt and note the station and pump. The supplier's records are the evidence.
    What fixes it
    Repair the vehicle and pursue the supplier. This is a claim rather than only a repair.

Codes that produce this symptom (29)

Listed with the codes that most typically present this way first — the likeliest place to start.

Information, not instruction

CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.

Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.

Others with this symptom

Be the first to write this up

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What makes one worth reading:

  • The car — make, model, year and engine. The same fault behaves differently on each.
  • What you measured, not only what you replaced.
  • What actually fixed it — or that nothing did, which is worth knowing too.

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