Powertrain, generic (extended)

P2D2B Hybrid/EV Battery Pack Coolant Temperature Sensor A/B Correlation

Check engine lightOn
EmissionsNot relevant
Drive cycleRequired
Limp modePossible

Liquid-cooled traction batteries often have coolant sensors at pack inlet and outlet. When the pack has rested long enough, sensors A and B should agree; P2D2B records a gap beyond the limit without naming the faulty one. No manufacturer documents P2D2B publicly. GM's 2019 hybrid tables test the pack inlet sensor alone under P0C43: after all high-voltage contactors have been open for at least 14,400 s, it fails only when it is off from both references, by 23 °C or more from the average cell temperature and by 22 °C or more from outside air, Type B. California asks for monitoring of every input used for battery thermal management. A wrong reading can make heating or chilling of the pack misjudge, limiting charging or power.

Likely causes

One pack coolant sensor has drifted
Corroded or loose connector at a sensor
Air trapped in the battery coolant loop after service
Faulty measuring input in the battery control module

Symptoms

  • Hybrid or EV battery warning
  • Reduced charging power or range
  • Battery heater or chiller running unexpectedly

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–500
Time0.5–3 h

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

Parts involved

hv battery pack coolant temp sensor ahv battery pack coolant temp sensor bbms

Related codes

P0C43P0CD6P0C42P0CD5P0ECAP2D2A

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