AdBlue warning and no-restart countdown on VW Group diesels

Which cars and engines are affected?

Audi, Volkswagen, SEAT and Škoda diesels that use AdBlue, the fluid the selective catalytic reduction (SCR) system injects into the exhaust to cut nitrogen oxides (NOx). If you are not sure whether your car uses AdBlue, put the registration in the enquiry form and we will check.

Published repair cases describe the fault on the Audi Q5 2.0 TDI built from 2013 to 2017, and say comparable models are affected. For other work on these cars, see our Audi and VW specialist page.

What are the symptoms?

• an AdBlue warning with a countdown to no restart, for example 600 miles
• the engine warning light and the glow-plug light come on
• the car otherwise drives normally
• an SCR fault message with nothing stored in the engine control unit

When you book, tell us the message on the dashboard, the distance left and when it first appeared.

What causes it?

The warning means the system cannot confirm that it is treating the exhaust as it should. Known causes on these cars include:

• a fault in the heater circuit of the AdBlue delivery module
• a faulty pressure sensor in the delivery module
• damaged wiring to the AdBlue injector
• crystallised AdBlue at the injector
• a NOx sensor giving implausible readings

How do you confirm the fault before fitting parts?

A fault code is not a repair, and these faults look alike from the driver’s seat. Before we quote for parts, we:

• scan every control unit, including the exhaust aftertreatment unit, because SCR faults may not show in the engine’s fault memory
• run a spray test on the AdBlue injector into a container
• run the delivery module and check that the pressure sensor reading is plausible
• check the wiring to the injector, heater and sensors
• read the NOx sensor live values: a reading stuck at zero points to the sensor itself

Some faults only come back after a period of mixed driving, so the tests can include a road test. We then show you what we found and send a written price. No part is fitted until you give your written approval.

What does the repair involve?

• Replace only the proven part, using the correct part for your car.
• Refill the system and run a dosing test to confirm it is working.
• Reset the warning with our diagnostic equipment once the fault is fixed.

Once the work is done, we check that the warning has cleared and verify the repair, including a road test where appropriate. We repair AdBlue and other emissions systems; we never remove or disable them.

Can the AdBlue system be removed or switched off?

Not by us. In the MOT, testers check visible SCR parts, and emissions equipment that is missing, obviously modified or obviously defective is a Major defect. So is an engine warning lamp that shows a fault on a diesel first used from 1 July 2008.

The Department for Transport consulted in 2026 on tighter rules against emissions tampering, naming AdBlue deletion alongside DPF removal.

How long does an AdBlue repair take?

It depends on what the tests find. Some faults only show after a road test, and some parts may need ordering.

Before any work starts, you get a written price and a promised time for your next update. If the car needs to stay with us, ask about a courtesy car when you book.

Is there a recall for the AdBlue system?

Whether a recall applies depends on the individual car, so check your registration on gov.uk. Recall work is done by the manufacturer’s network, not by us.