What AdBlue actually is
What is AdBlue — adBlue is not a fuel and it never enters the engine. It is AUS 32 — 32.5% high-purity urea in demineralised water — dosed into the exhaust ahead of the SCR catalyst, where it becomes ammonia and converts NOx to nitrogen and water.
Call 01295 380724 From just £89 call-out fee
What is AdBlue — the detail
It is a chemical reagent, not a fuel or an additive
Nothing you pour into the AdBlue tank reaches the combustion chamber. The fluid travels from its own tank, through its own pump and its own heated lines, to an injector in the exhaust. This is why the two directions of contamination are entirely different failures.
The chemistry
In the hot exhaust the urea decomposes, via an intermediate, to ammonia and carbon dioxide. Across the catalyst the ammonia reacts with nitrogen oxides to produce nitrogen and water vapour. That reaction is the whole purpose of the system.
The physical properties that cause problems
Density around 1.09 g/cm³, against diesel at roughly 0.83 — which is why it sinks in a fuel tank instead of mixing. It freezes at about −11 °C and expands roughly 7% doing so. It crystallises white as it dries, and it is corrosive to copper, brass, aluminium, zinc, mild steel and some plastics.
What it is not
It is not an additive, it is not a fuel treatment, it is not an antifreeze, it does not clean anything, and it does nothing whatsoever for the DPF.
Why the two directions differ so much
AdBlue in the fuel tank is a fuel-side contamination: drain, flush, filter, and the SCR system is untouched. Fuel in the AdBlue tank is hydrocarbon contamination of a precision dosing circuit and a catalyst — a genuinely different job at a genuinely different price.
Common questions
Does AdBlue go in the engine?
No, never. It is dosed into the exhaust, downstream of the engine, ahead of the SCR catalyst.
Is AdBlue dangerous to handle?
It is low hazard — rinse skin and eyes with water, and keep it off alloy, chrome and bare metal because it corrodes them.
Does AdBlue improve fuel economy or performance?
No. It reduces NOx emissions. It does nothing for power or economy.
£89 is the call-out. An AdBlue tank drain and flush is quoted on the phone before a technician travels. If the SCR system needs component replacement — dosing injector, pump, tank or catalyst — that is separate, and you will be told before any work starts. If this is a job we cannot fix at the roadside, we will tell you that on the phone rather than after we arrive.
More explainers
If something has already gone wrong
What customers say
4.8 out of 5 from 2,190 Trustpilot reviews. What reviewers mention most is that the technician stayed calm and professional with a driver who was embarrassed and stressed, and that somebody arrived when they said they would.
The most common criticism is price. People do not expect a wrong-fluid job to cost what it costs, and that is a fair complaint to publish rather than bury. The answer is the From just £89 call-out fee, a quote given on the phone before a technician travels, and being told when a job cannot be done at the roadside rather than after somebody has arrived and charged for the visit.
Who you are dealing with
Work booked through AdBlue in Fuel is carried out by Fuel Fixer Ltd, company no 08520551, registered at Fairway House, Portland Road, East Grinstead, RH19 4ET, trading as Forecourt Assist and part of Fuel Fixer International, which is owned by Stockbridge Capital Holdings.
Reference: NOx (Wikipedia).
Across the Fuel Fixer network
Every brand above belongs to Fuel Fixer International, owned by Stockbridge Capital Holdings. The directory lives on the operator's own site: forecourtassist.co.uk/network.