Powertrain, generic · Hybrid propulsion

P0CD9 Hybrid/EV Battery Pack Coolant Temperature Sensor B Circuit Intermittent/Erratic

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P0CD9 covers a signal from battery coolant temperature sensor B that drops out or jumps for short moments while staying inside the electrical limits most of the time. It is meant for loose terminals, chafed wires or a sensor that misbehaves only with vibration or temperature. Volvo documents ECM-P0CD900 as a permanent entry on several 2021-2022 plug-in hybrids: according to TJ 36929, charging in outside air warmer than 20 °C can light the engine lamp although nothing is broken, and software release 2024 week 34 (version 3.2.4) improves the detection; in any other situation VIDA fault tracing applies. GM does not list P0CD9 and handles the comparable erratic case for sensor A as P0C46 with a step-sum test. Hard short or open faults are P0CD7 and P0CD8.

Likely causes

False detection after charging in warm weather (Volvo, software update)
Loose or corroded terminal at the sensor or module connector
Chafed harness that moves with the battery or body
Sensor B with an intermittent internal fault

Symptoms

  • Check engine light, often after charging
  • Jumping outlet temperature value in live data

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€0–400
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 bwiring harnessbms

Related codes

P0CD7P0CD8P0CD5P0C46

References: static.nhtsa.gov, gsi.ext.gm.com, law.cornell.edu.