Powertrain, generic (extended)

P2B25 Hybrid/EV Electronics Coolant Temperature Sensor C Circuit Range/Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P2B25 is the plausibility code for the third electronics coolant sensor. The signal is electrically sound, but its value cannot be right, for example because sensor C still reads cold while sensors A and B in the same loop have long warmed up, or because it jumps by an amount the coolant could not follow. No manufacturer publishes a set condition for P2B25. NTN-SNR describes it as a deviation or malfunction of the sensor C signal, and CARB asks for rationality checks on inverter thermal management inputs. GM's after-soak comparison for sensor A (P0CEF) illustrates the method. A sensor C that sits near a component with its own heat, such as the charger, can also mislead the test if the pump has stopped or the loop holds air. Electrical faults of sensor C go to P2B26 and P2B27.

Likely causes

Sensor C reading drifted away from the true temperature
Air in the loop or a weak pump leaving sensor C without flow
Corrosion in the sensor C connector

Symptoms

  • Fault code set after a cold start or a long drive
  • Cooling system reacting inconsistently
  • Possible limitation of charging power

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€40–450
Time0.5–2.5 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

P2B24P2B26P2B27P2B21P0CEF

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