P023B: Charge Air Cooler Coolant Pump A Control Circuit Low

Some engines cool the charge air with a coolant-to-air cooler in its own low-temperature circuit, driven by an electric pump – GM uses this on supercharged V8s such as the LT4 (Camaro ZL1, Corvette Z06, CTS-V) and LT5 (Corvette ZR1). P023B means GM's driver diagnosis has found a short to ground (0.5 Ω or less between output and ground with the driver off). Bundled conditions: main relay at least 11 V, ignition above 5 V; 50 of 63 samples set the code with the warning light in the first trip on 2018–2019 engines, older modules need two trips. Without the pump the charge air gets hot and boost is limited.

Medium severity. Can I keep driving?Watch the temperature gauge. If it climbs or a warning appears, stop the car in a safe place and turn off the engine: overheating can cause serious damage.

Symptoms

Check engine light on
Loss of power under load or in heat (boost limited)
Follow-up code P026A possible

Most likely causes

Control wire to the pump shorted to ground
Pump shorted internally
Moisture or corrosion in the connector
Driver stage in the engine module faulty

What to check, in order

Start with the simplest. You can tick off each step.

With the engine cold, check the coolant level; never do this when the system is hot
With the connector unplugged, check whether the signal wire is making contact with ground.
Check the actual temperature in live data
Make sure the fan comes on when it should
Check the thermostat and connector
Measure the sensor and replace it if its readings do not make sense

Good to know

Repair difficulty: medium
It can trigger limp mode.
It affects emissions.

What each character of P023B means

P: Powertrain: engine and transmission
0: Generic code: same on every make
2: Fuel injection
3B: Specific fault in that system

Frequently asked questions

Can I keep driving with code P023B?

Watch the temperature gauge. If it climbs or a warning appears, stop the car in a safe place and turn off the engine: overheating can cause serious damage.

What causes code P023B?

The most common causes are: control wire to the pump shorted to ground; pump shorted internally; moisture or corrosion in the connector.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.