OBD-II code · Network
U040A Invalid Data Received From Air Conditioning Control Module
A receiving module detected implausible data from the A/C control module. Compressor enable, blower or refrigerant pressure values fail plausibility checks against other inputs and are rejected.
Is it safe to drive with U040A?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyModule internal fault or sensor input drift
- PossibleSoftware version mismatch after replacement
- Less likelyGateway module routing CAN messages incorrectly
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
- AC Control Module
Related codes
- U0407Invalid Data Received from Steering Angle Sensor Module
- U0408Invalid Data Received from Vehicle Immobilizer Control Module
- U0409Invalid Data Received from Vehicle Security Control Module
- U040BInvalid Data Received From Exhaust Gas Recirculation Control Module A
- U040CInvalid Data Received From Exhaust Gas Recirculation Control Module B
- U040DInvalid Data Received From Turbocharger/Supercharger Control Module A
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.