Engine

P023B — Charge Air Cooler Coolant Pump Control Circuit Low

Severity: medium Drive with care, to a shop

What P023B means

On engines with a liquid-cooled intercooler, the ECM runs an electric pump that circulates coolant through the charge air cooler. P023B sets when the voltage in the pump control circuit is lower than expected. Typical reasons are an open or shorted wire, a poor connection, or a failing pump or relay. The result can be hotter intake air after the turbo.

Symptoms

  • Check Engine light on
  • Reduced power under boost
  • High intake air temperature
  • Poor fuel economy
  • Possible reduced-power mode

Possible causes

  1. Failed charge air cooler coolant pump
  2. Damaged wiring or connector in the pump control circuit (open, short to ground, corrosion)
  3. Bad pump relay or blown fuse
  4. Low system voltage from a weak battery or charging fault
  5. Rarely, an internal ECM fault

How to diagnose

  1. Scan all codes and freeze-frame data, noting any voltage or intake air temperature codes
  2. Check the fuse and relay for the intercooler pump
  3. Inspect the pump harness and connector for chafing, corrosion or heat damage
  4. Test battery voltage and alternator output
  5. Command the pump on with a scan tool and see whether it runs
  6. Measure power, ground and control signal at the pump connector with a multimeter
  7. Test the control wire back to the ECM for opens and shorts
  8. Check the coolant level in the intercooler loop and bleed any air

Common fixes

  • Repair the wiring or replace the damaged connector
  • Replace the pump relay or fuse
  • Replace the charge air cooler coolant pump
  • Fix the low-voltage cause: battery or alternator
  • Top up and bleed the intercooler coolant loop

Questions and answers

What does P023B mean?

The ECM detected low voltage in the control circuit of the charge air cooler coolant pump. The cause is most often wiring, the relay, or the pump itself.

Can I drive with P023B?

Short trips at light load are usually fine. Poor intercooling reduces power and fuel economy, so do not put off the repair.

How do I quickly test the intercooler pump?

Check the fuse and relay, then command the pump on with a scan tool. If it stays silent, measure power and ground at its connector.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.