Symptoms
- DEF or AdBlue icon lit with a range countdown
- No change in how the car drives at first
- Vehicle may limit top speed or refuse to restart if fluid runs out completely
Likely causes
- CommonDEF tank running low from normal useDEF is consumed gradually as part of normal diesel emissions control.
- PossibleDEF tank emptyMany systems will prevent the engine from restarting once truly empty, by design.
- Less commonFaulty DEF level sensorCan show incorrect levels even with adequate fluid.
What to do
- Check the estimated remaining range shown with the warning.
- Buy diesel exhaust fluid (DEF) from an auto parts store, gas station, or dealer.
- Locate the DEF fill port, usually near the fuel filler or under the hood, and check your manual for the exact spot.
- Fill following the container's instructions, being careful not to spill it on painted surfaces since it can be corrosive to some finishes.
- Restart the vehicle and confirm the warning clears or the range estimate increases.
- Don't let the level get to zero, since many vehicles won't restart until DEF is added.
Tools and parts
- Funnel dedicated to DEF only
Diesel exhaust fluid (DEF/AdBlue)Search: “DEF fluid jug, correct size for your vehicle”
When to call a pro
No professional needed for a normal refill; see a dealer or diesel specialist if the warning persists after filling or if the sensor seems inaccurate.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.