Owner decision guide
Gasoline was put in a diesel vehicle
Do not start the engine or switch the ignition on. Gasoline reduces diesel-fuel lubricity and can circulate through expensive high-pressure components; the safest response is towing and a system drain using manufacturer procedures. Before acting, check Whether ignition or engine was operated, Approximate amount and fuel type added, Vehicle’s low-pressure priming behavior. Record the exact condition, since temperature, speed, load and warning status all change the diagnosis. The sections below break this down further: if you catch it at the pump, if you already started it, what it costs and why, insurance and prevention. This is rated stop driving risk: If the engine was run, stop it as soon as safely possible and tell the repairer exactly how far it operated. 4 related questions are answered separately below. Reviewed under this site's evidence-first standard, sourced to NHTSA vehicle and recall guidance, with related diesel ownership guides linked at the end.
Evidence first
Gasoline in a diesel tank is one of the few fuelling mistakes that can destroy an engine's injection system in a single drive. Diesel fuel lubricates the high-pressure pump and injectors; gasoline is a solvent that strips that lubrication away.
The single most important thing is not to start the engine.
If you catch it at the pump
Nothing has entered the engine yet, so the damage is contained to the tank.
- Do not start the engine, and do not turn the key to the run position on some vehicles
- Do not move the vehicle under its own power
- Have it towed to a shop that can drain and flush the system
- Tell them exactly how much gasoline went in and whether the engine was started
- Expect the tank drained, lines flushed and filters replaced
If you already started it
Stop as soon as it is safe. Every minute of running circulates gasoline through the high-pressure pump.
Symptoms include rough running, knocking, loss of power, heavy smoke and eventually stalling. Once the engine stops on its own, do not attempt to restart it.
What it costs and why
Modern common-rail diesel injection operates at extremely high pressure with clearances measured in microns, lubricated entirely by the fuel.
Running gasoline through it causes metal-to-metal contact and generates debris that circulates through the whole system. That is why a contaminated system usually needs the pump, injectors, rail and lines addressed instead of just a tank drain: the debris does not stay in one place.
Insurance and prevention
Many comprehensive policies cover misfuelling, sometimes as a specific provision. It is worth checking before paying out of pocket, and worth reporting promptly.
Prevention is mostly labelling: a bright filler-cap label, and a moment's attention at an unfamiliar pump. Diesel nozzles at truck lanes are larger and will not fit most gasoline filler necks, but the reverse is not true. A gasoline nozzle fits a diesel filler easily.
What to check before acting
| # | Check | Why it matters |
|---|---|---|
| 01 | Whether ignition or engine was operated | Record the exact condition; differences in temperature, speed, load and warning status change the diagnosis. |
| 02 | Approximate amount and fuel type added | Record the exact condition; differences in temperature, speed, load and warning status change the diagnosis. |
| 03 | Vehicle’s low-pressure priming behavior | Record the exact condition; differences in temperature, speed, load and warning status change the diagnosis. |
Record the exact condition; differences in temperature, speed, load and warning status change the diagnosis.
Record the exact condition; differences in temperature, speed, load and warning status change the diagnosis.
Record the exact condition; differences in temperature, speed, load and warning status change the diagnosis.
Safe sequence
What to do next
| Step | Action |
|---|---|
| 1 | Do not cycle the ignition |
| 2 | Move the vehicle only by approved towing |
| 3 | Have the tank and affected fuel system drained and inspected |
- 1
Do not cycle the ignition
- 2
Move the vehicle only by approved towing
- 3
Have the tank and affected fuel system drained and inspected
Avoid making it worse
What not to do
- Do not dilute it by adding more diesel
- Do not attempt to drive to a shop
If the engine was run, stop it as soon as safely possible and tell the repairer exactly how far it operated.
Source and scope
Common questions
What happens if I put gasoline in a diesel?
Gasoline strips the lubrication that the high-pressure pump and injectors depend on, causing rapid wear and debris that contaminates the whole system. It can destroy the injection system in one drive.
Should I start the engine to move it?
No. Do not start it or move it under its own power. Have it towed so the damage stays confined to the tank.
How much gasoline is too much?
Treat any amount as requiring a drain and flush. Even a small proportion reduces the fuel's lubricity, and the cost of being wrong is an injection system.
Does insurance cover misfuelling?
Many comprehensive policies do, sometimes as a specific provision. Check with your insurer before paying out of pocket, and report it promptly.