OBD-II code · Network
U02A9 Lost Communication With Charge Air Cooler Coolant Pump A
The vehicle bus reports loss of communication with charge air cooler (intercooler) coolant pump A. Intake-charge cooling on indirect intercooler systems cannot be controlled, raising knock risk and reducing power.
Is it safe to drive with U02A9?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
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
- Cac Coolant Pump A, Vehicle Bus Wiring
Related codes
- U01BCLost Communication With Charge Air Cooler Coolant Pump B
- U02A6Lost Communication With Safety Integration Control Module
- U02A7Lost Communication With Engine Sound Control 1
- U02A8Lost Communication With Engine Sound Control 2
- U02AALost Communication With Engine Disconnect Clutch
- U02ABLost Communication With Vehicle Thermal Management Control Module
- U02ACLost Communication With Turbocharger/Supercharger Boost Control A
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.