Powertrain, generic (extended)

P2CAD Charge Air Cooler Coolant Pump B Control Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

Where a charge air cooling loop has a second electric pump, it carries the letter B. P2CAD reports that the control line to that pump is open, so the driver stage in the engine computer sees no load. No manufacturer documents a pump B or this code publicly. GM publishes the matching test for pump A (P023A) on the supercharged LT5 in table 19OBDG03A: with the low-side driver switched off, more than 200 kΩ between output and ground counts as open; 50 failed samples out of 63 at 100 ms, main relay at least 11 V, Type A with MIL on the first trip. Unplugged or corroded connectors, a broken wire or an open motor winding are the common finds. A pump driven only over LIN has no such line and would report through U01BC instead.

Likely causes

Pump B connector loose, unplugged or corroded
Broken control wire between engine module and pump B
Open motor winding or internal board fault in pump B

Symptoms

  • MIL on, often after the first trip
  • Pump B silent; charge air temperature rises under load
  • Reduced engine power

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

P2CAEP2CAFP023AP2CB0U01BC

References: law.cornell.edu, gsi.ext.gm.com, rheinmetall.com.