Powertrain, generic (extended)

P2B26 Hybrid/EV Electronics Coolant Temperature Sensor C Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

The voltage on the signal line of sensor C, the third coolant sensor in the power electronics loop, is lower than the controller accepts. Low means voltage here, not temperature: on an NTC sensor it corresponds to an implausibly hot value. A pinched or chafed lead touching the body, a short inside the sensor or coolant that has crept into the plug are the usual findings. No manufacturer documents P2B26 publicly; the NTN-SNR catalogue describes a signal of sensor C that is too small. CARB requires inverter cooling inputs to be checked for values outside their range; for sensor A, GM uses 4 % of the reference (0.2 V) as the lower limit. Since the reading suggests overheating, controllers tend to run pump and fans hard and may reduce power. The open or high case is P2B27, a plausible but wrong value P2B25.

Likely causes

Sensor C signal lead pinched or chafed against ground
Coolant wicking into the sensor plug
Shorted sensor C element

Symptoms

  • Warning lamp or system message
  • Pump and radiator fan running hard even when cool
  • Reduced power in some situations

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€40–400
Time0.5–2 h

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

Parts involved

hybrid electronics coolant temp sensor cwiring harnesshybrid control module

Related codes

P2B27P2B24P2B25P2B22P0CF0

References: law.cornell.edu, ntn-snr.com, gsi.ext.gm.com.