Powertrain, generic (extended)

P2BDB Motor Electronics Coolant Temperature Sensor B Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2BDB tells that the signal of coolant temperature sensor B sits above its valid voltage range. With a thermistor fed from a 5 V reference through a pull-up resistor, a broken wire, an unplugged connector or a sensor gone open lets the voltage rise to almost the reference, which the module would read as extreme cold. No manufacturer documents P2BDB publicly. GM's sensor A counterpart on the 2013 Two-Mode hybrid trucks, P0A03, uses a limit of -59.1 °C and the same 30-of-50 count at 100 ms, Type B. Since real overheating would go unseen, controllers usually fall back to a safe pump speed or reduced power. P2BDA covers the grounded case, P2BD8 an unspecified circuit fault of the same sensor.

Likely causes

Sensor B connector unplugged, not latched or with a backed-out pin
Broken signal or ground wire of sensor B
Sensor B thermistor gone open
Signal wire shorted to a voltage source

Symptoms

  • Check engine light or hybrid warning
  • Scan tool shows an implausibly low electronics coolant temperature
  • Electronics coolant pump running at a fixed high speed

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€40–500
Time0.5–2.5 h

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

Parts involved

motor electronics coolant temp sensor bwiring harnesshybrid control module

Related codes

P2BD8P2BD9P2BDAP2BDFP0A03

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