Powertrain, generic (extended)

P2B27 Hybrid/EV Electronics Coolant Temperature Sensor C Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2B27 is logged when sensor C in the power electronics coolant loop sends a signal near the top of the reference, which the controller would have to read as deep frost. Far more often than real cold, the reason is a circuit that has opened: a connector that has backed out, a terminal pushed out of its cavity, a broken wire near a moving part or a failed element; shorting to the battery feed is rarer. No manufacturer documents P2B27 publicly; NTN-SNR names an excessive sensor C signal. As an order of magnitude, GM flags its sensor A above 98 % of the reference (P0CF1). CARB counts these sensors as monitored inverter cooling inputs. Unlike the low fault, a cold reading can hide real heat, so the controller usually switches to a substitute value and limits power. P2B26 is the grounded counterpart.

Likely causes

Connector backed out, terminal pushed out or wire broken
Sensor C element open
Signal line shorted to battery voltage

Symptoms

  • Warning lamp and hybrid system message
  • Sensor C shown far below outside temperature in live data
  • Limited electric power

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€30–600
Time0.5–3 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

P2B26P2B24P2B25P2B23P0CF1

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