Put Diesel in the AdBlue Tank?
On many vans and cars the AdBlue filler sits right next to the diesel filler, so a nozzle in the wrong hole takes a second. Diesel in the AdBlue tank must be drained before the engine runs - we come to you 24/7 across London, Essex and Sussex.
Call for AdBlue Tank Drain: 07393 440 255Why diesel in the AdBlue tank is a problem
The AdBlue tank feeds a pump, a quality sensor and a dosing injector in the exhaust. Anything other than AdBlue in it puts every one of those parts at risk - but as long as the engine stays off, the problem stays in the tank.
Diesel is lighter than AdBlue, so it floats on top rather than mixing. That is exactly what makes it dangerous: the quality sensor at the bottom of the tank may not notice anything at first, and the car can seem fine until the level drops or the fluid sloshes and diesel is drawn into the pump.
Diesel is an oil. It swells and degrades the rubber seals in the AdBlue pump module, blocks the fine spray holes in the dosing injector, and if it reaches the SCR catalyst it coats the honeycomb and stops it working. Replacing the pump module alone is commonly a four-figure job at a dealership.
Warning signs of diesel in the AdBlue tank
- AdBlue malfunction or quality warning, sometimes only after several miles
- Countdown to 'no restart' on the instrument cluster
- Diesel smell at the AdBlue filler; oily film visible in the neck
- White or grey smoke and a strong smell from the exhaust if contaminated fluid has been dosed
Immediate action required:
Do not start the engine. If it is running, switch it off as soon as it is safe to do so.
Do not top the tank up with AdBlue to 'dilute' it - the whole tank has to be drained.
Call 07393 440 255. Tell us the vehicle and roughly how much went in, and we will give you a fixed price.
How we fix diesel in an AdBlue tank
- Complete drain of the contaminated AdBlue tank through the filler
- Tank and pick-up flushed with fresh AdBlue until it runs clean
- Pump filter and quality sensor checked
- Refill with fresh ISO 22241 AdBlue
- Fault codes cleared and the system checked with diagnostics
- Contaminated fluid disposed of as hazardous waste
Already started or driven the vehicle?
Because diesel floats, having driven a few miles does not automatically mean the system is damaged - but it does mean we need to act quickly. We drain the tank completely, flush it with fresh AdBlue until it runs clean, check the pump filter, refill and clear the codes. If the dosing injector has been affected we can advise on the next step.
Other AdBlue mix-ups we fix
Diesel in AdBlue Tank FAQs
Common questions about diesel in an AdBlue tank.
I put diesel in the AdBlue tank but haven't started the car - what should I do?
Leave it switched off, don't drive it, and call us. With the engine off the diesel is sitting on top of the AdBlue in the tank and can be drained out cleanly. Starting the engine is what pumps it into the system.
Diesel floats on AdBlue - can I drive with just a small amount in the tank?
No. As the AdBlue level drops, or when the fluid moves about on the road, the diesel reaches the pump pick-up. Even a small amount can block the dosing injector and damage the pump seals, and that repair costs far more than a drain.
What are the symptoms of diesel in the AdBlue tank?
Often nothing at first, because diesel floats above the quality sensor. Later you may see an AdBlue malfunction warning, a countdown to 'no restart', a diesel smell at the AdBlue filler, or white smoke and a strong smell from the exhaust if the mixture has been dosed.
Can you drain an AdBlue tank at the roadside?
Yes. AdBlue tanks have no drain plug, so we pump the contents out through the filler with dedicated equipment, flush with fresh AdBlue, refill and clear the codes - at the forecourt, roadside, your home or your depot. Cars, vans and trucks are all covered.