Powertrain, generic (extended)

P2CAE Charge Air Cooler Coolant Pump B Control Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2CAE concerns the second electric pump of a charge air cooling loop: its control line is held at ground potential where the driver expects a higher level. No manufacturer documents pump B publicly. GM's published test for pump A (P023B, LT5, table 19OBDG03A) runs with the low-side driver off and flags a short to ground when output and controller ground are connected by less than 0.5 Ω, again 50 of 63 samples, Type A. What the pump then does depends on its design: a plainly switched motor may run all the time, while a smart pump that reads a missing PWM signal may fall back to an emergency mode. Look for a harness chafed on a bracket, water between pins, or an internal short in pump B. The opposite fault, a short to power, is P2CAF.

Likely causes

Control wire of pump B rubbed through to ground
Water or corrosion in the pump B connector
Internal short in the electronics of pump B

Symptoms

  • MIL on
  • Pump B runs continuously or stays in a fallback mode
  • Possible power reduction when the charge air gets hot

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€30–700
Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

cac coolant pump bwiring harnessecm

Related codes

P2CADP2CAFP023BP2CB0

References: law.cornell.edu, gsi.ext.gm.com, patents.google.com.