# What are the symptoms of old fluid | answered

> What are the symptoms of old fluid: Usually nothing you can feel — a dosing or NOx conversion fault appears, often after several driving cycles.

- URL: https://adblueinfuel.co.uk/answers/what-are-the-symptoms-of-old-fluid/
- Focus: what are the symptoms of old fluid
- Updated: 2026-11-02
- Phone: 01293 248666 (Call-out from £89)
- Publisher: AdBlue in Fuel — a service by Forecourt Assistance — Forecourt Assistance is a trading name of Fuel Fixer Ltd, company no 08520551, registered at Fairway House, Portland Road, East Grinstead, RH19 4ET, a company of Fuel Fixer International.

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## What are the symptoms of old fluid
Short answerWhat are the symptoms of old fluid — usually nothing you can feel — a dosing or NOx conversion fault appears, often after several driving cycles.

Call 01293 248666 Call-out from £89

Tap for soundTap to callAnswered by Rambo S, Wrong Fuel Expert at Fuel Fixer International.

## What are the symptoms of old fluid — the context
Urea in solution is not indefinitely stable. It hydrolyses slowly to ammonia and carbon dioxide, and the rate rises sharply with storage temperature — which is why manufacturers quote shelf life against a temperature band rather than a flat date. Fluid stored warm for a long period, or in a part-used container that has been opened repeatedly, drifts below the 32.5% concentration and can also develop elevated biuret. The result is quiet under-dosing rather than any dramatic symptom.

Expired AdBlue degrades as urea slowly hydrolyses to ammonia, so the concentration drifts out of specification and the system under-doses. It is one of the cheaper faults to put right — drain, flush and refill. Call 01293 248666.

**The problem behind this question**
 | Topic | Expired AdBlue
 | Severity | Recoverable Normally put right by a drain and flush, provided the engine has not been run.
 | Typical cost | Call-out £89 to £199 · drain £199 to £1,999
 | Time on site | About 55 minutes
 | Helpline | 01293 248666
It is worth separating SCR from the DPF before acting on any advice. Both sit in the exhaust, both light a warning lamp, and the standard advice for one — a long run at motorway speed — does nothing at all for the other.

The call-out is £89 to £199. 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.

### Related reading

### Start here
Expired AdBlueWhat AdBlue actually isDriver inducementSCR vs DPF
### More answers
Does this affect my SCR system or the warning light?Can the tank be saved?Why does it happen more on short journeys?Can I make my own from urea and water?Is the fuel you drain out reusable?Surely AdBlue is mostly water anyway?Will it clear on its own if I top up?Why does my gauge say empty when I just filled it?Was live data read, or only the stored code?Will the SCR catalyst need replacing?
## 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 Call-out from £89, 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
This site is published by Forecourt Assistance, which operates AdBlue in Fuel. Forecourt Assistance is a trading name of Fuel Fixer Ltd, company no 08520551, registered at Fairway House, Portland Road, East Grinstead, RH19 4ET, a company of Fuel Fixer International. The group, Fuel Fixer International, is owned by Stockbridge Capital Holdings.

Reference: GOV.UK — vehicle approval.

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