DEF / AdBlue warning (diesel)
An AdBlue or DEF symbol, often with a countdown message.
GET CHECKED SOON
Get it looked at soon · Amber means get it checked
What it means
Many diesels use DEF (AdBlue) to clean their exhaust. When it runs low the car warns you, usually with a countdown of miles remaining.
Why it matters
By law these systems will prevent the engine from restarting once DEF is empty — so this is not a warning to ignore. Topping up DEF is inexpensive and you can often do it yourself, or we can.
Can I drive?
Yes, until the countdown gets low — but refill it well before it reaches zero, or you may be stranded unable to restart.
Warning-light symbols and meanings vary by vehicle - always check your owner’s manual. This is general guidance based on what the light indicates, not a physical inspection, and a light on its own never names a failed part.
Want to know what is causing the warning?
Auto Star can read the codes, inspect the vehicle, and find the underlying cause before recommending any repairs - you see what we find and approve the work first.