Yellow or Orange
Diesel Exhaust Fluid (DEF)
DEF is low or out of range for emissions control.
The diesel exhaust fluid light means your vehicle is running low on the fluid used to reduce harmful exhaust emissions. If this fluid is not replenished, your vehicle may eventually limit engine power or refuse to restart.
What to do
- 01Check your owner's manual to locate the specific DEF fill port for your vehicle.
- 02Purchase a bottle of diesel exhaust fluid from a local auto parts store or gas station.
- 03Carefully add the fluid to the reservoir while ensuring you do not overfill it.
- 04If the light stays on after driving for a short distance, contact Miles Tech Auto to schedule a diagnostic inspection.
Other common causes
Common causes include a faulty fluid level sensor, a compromised reservoir heater, a damaged wiring harness, or a malfunction within the selective catalytic reduction system.
How we check it
We test the fluid level sensor operation and check the emission system's control module for specific fault codes.
Symbols vary by make and model — always confirm in your owner's manual. If the light is red, the car feels different, or the light is blinking, stop and call us before driving further.