What it means
CAC coolant pump A control voltage above expected range. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Charge air cooler pump A circulates coolant through the charge air cooler to help control intake-air temperature. The control module monitors the pump A control circuit and sets this code when its voltage is higher than expected, which can happen if the circuit is shorted to battery or has a poor connection.
Common causes
Most likely first.
- Wiring shorted to battery
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
Symptoms
- Check-engine light on
- Reduced engine power or acceleration
- Poor turbo response
- Reduced fuel economy
How to diagnose it
- Check freeze-frame data and pump-related live data to see when the fault occurred and whether pump A was being commanded.
- With the circuit fault present, carefully wiggle the pump A harness and connectors while watching the scan data for a change.
- Inspect pump A wiring and connector seals for chafing, water ingress, corrosion, pushed-back pins, or contact with a B+ source.
- With the circuit powered down as specified by the manufacturer, check the control wire for a short to battery and inspect connector pin fit.
- If wiring and connections are sound, test pump A and its control circuit against the manufacturer's diagnostic procedure.
Common fixes
- Repair chafed or pinched pump A wiring and secure it away from battery-positive wiring.
- Clean or replace a corroded connector and restore proper pin fit and sealing.
- Repair a shorted control wire or damaged connector.
- Replace charge air cooler coolant pump A if testing confirms an internal fault.
Can I keep driving?
If power is reduced, avoid hard acceleration and sustained boost; a malfunctioning cooler pump can raise intake-air temperatures and worsen performance. Stop if the engine overheats or runs abnormally.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.