OBD-II code · Network
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.
Is it safe to drive with U0645?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyBus wiring open or shorted
- PossibleModule without power or ground
- PossibleModule failed
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.5–3 h
- Emissions test
- Usually unaffected
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Active Air Dam Module, Vehicle Bus Wiring
Related codes
- U0642Lost Communication With EVAP System Pressure Sensor/Switch Circuit B
- U0643Lost Communication With Turbocharger/Supercharger A Temperature Sensor
- U0644Lost Communication With Wastegate Position Sensor A
- U0646Lost Communication With Motor Electronics Coolant Pump A
- U0647Lost Communication With Motor Electronics Coolant Pump B
- U0648Lost Communication With Motor Electronics Coolant Pump C
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.