Question 1

What happens if you accidentally put AdBlue in a diesel tank?

Accepted Answer

AdBlue is water-based and denser than diesel, sinking to the tank bottom. It causes rapid rust corrosion on steel fuel components and crystallizes when heated, destroying high-pressure fuel pumps and injectors.

Question 2

What if I only put a small amount of AdBlue in my diesel tank?

Accepted Answer

Even a tiny amount (e.g. 0.5 to 1 litre) can cause catastrophic injector failure because AdBlue does not mix with diesel; it sits right at the fuel pump intake. The tank must still be drained before starting.

Question 3

How much does AdBlue in a diesel tank repair cost in the UK?

Accepted Answer

If the engine was left off, a mobile roadside AdBlue drain and chemical flush typically costs between £250 and £450. However, if the engine was started, repair bills range from £3,000 to £5,000+ at main dealers.