U0645
Lost Communication With Active Air Dam Module
The vehicle bus reports loss of communication with smart active air dam module. The lower-front aero spoiler stays in its default position; aerodynamic drag and front-end cooling can change.
The vehicle bus reports loss of communication with smart active air dam module. The lower-front aero spoiler stays in its default position; aerodynamic drag and front-end cooling can change.
Common causes
- high
Bus wiring open or shorted
One of the most commonly reported causes for this code — check this first.
Typical part cost: $130-1650
- medium
Module without power or ground
A plausible cause — test and verify before replacing parts.
Typical part cost: $130-1650
See all causes + fix costs
Create a free Wrenchify account to unlock the rest for U0645.
Unlock causesFree forever · No credit card
First things to check
- 1Confirm the code with a scan tool and check for additional related codes.
- 2Inspect the relevant sensors, wiring, and connectors for damage or corrosion.
Get the full step-by-step diagnosis
Create a free Wrenchify account to unlock the rest for U0645.
Unlock diagnosisFree forever · No credit card
Related codes
See related trouble codes
Create a free Wrenchify account to unlock the rest for U0645.
Unlock related codesFree forever · No credit card
Frequently asked questions
What does U0645 mean?
U0645 means "Lost Communication With Active Air Dam Module". It is a generic OBD-II code that points to a fault in the network / communication.
What are the most common causes of U0645?
bus wiring open or shorted; module without power or ground; module failed — these are the most commonly reported causes. Verify with a proper diagnosis before replacing parts, or use the Wrenchify app for a vehicle-specific diagnosis.
Can I keep driving with this code?
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical. Use the Wrenchify app for a full diagnosis specific to your vehicle.
Get the full U0645 diagnosis for your vehicle
Year, make, model + step-by-step repair help — free plan included.