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.
Related Driver Help
Related warning lights
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.