P023B: Charge Air Cooler Coolant Pump A Control Circuit Low
What to do
Ask for the charge air cooler's own coolant circuit to be checked, including its level. This system has a separate reservoir from the engine's, it is easy to overlook at a service, and a pump running dry both fails and produces this fault.
Expect the car to feel flat under sustained load — a long hill, a heavy load, or hard acceleration — while feeling normal around town. That pattern fits this fault and is worth reporting.
It is not an emergency but do not leave it for months. Hot intake air makes the engine pull timing to protect itself, which costs performance and economy, and sustained high intake temperatures are hard on the engine.
What this code means
The control circuit for the charge air cooler's coolant pump is sitting lower than the module commanded.
This code belongs to a liquid-cooled intercooler, which is worth establishing first because many engines do not have one. A conventional intercooler is an air-to-air radiator in the front bumper with no moving parts. A liquid-cooled charge air cooler sits on or near the intake manifold and has its own low-temperature coolant circuit with its own electric pump — a second, separate cooling system running cooler than the engine's.
So the pump is the part this code is about, and its failure is thermal rather than dramatic. Nothing overheats immediately. The charge air simply stops being cooled, so intake temperature climbs, the module pulls timing to protect the engine from knock, and the car feels flat under sustained load while running perfectly at light throttle.
A circuit reading low points at a short to ground, a failed driver in the module, or a seized pump drawing enough current to drag the line down. The usual separation applies: unplug the pump and see whether the circuit recovers.
Check the low-temperature circuit's coolant level before anything electrical. It is a separate reservoir from the engine's, it is frequently overlooked at service, and a pump run dry both fails and reads exactly like this.
Likely causes
Start here
- Wiring shorted to ground · moderate
- Seized pump motor · moderate
- Corroded or loose connector · easy
Less common
Rare
- Failed control module output driver · specialist
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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