Powertrain, generic (extended)

P2B23 Hybrid/EV Electronics Coolant Temperature Sensor B Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

With P2B23 the signal of electronics coolant sensor B climbs close to the reference voltage. For an NTC sensor that reads as extreme cold, which in practice nearly always points to an interruption: an unplugged or water-damaged connector, a broken signal or ground lead, an open element, or more rarely a short to a voltage source. No manufacturer documents P2B23 publicly; NTN-SNR records it as signal too high for sensor B. GM's tables for the sibling sensor A code P0CF1 set above 98 % of the reference (4.9 V) for 4 s in a 5 s window, Type B with MIL after two trips. A real-world hint comes from sensor A on the Chrysler Pacifica Hybrid, where water in an inline connector caused the same kind of high reading. The grounded counterpart is P2B22.

Likely causes

Open signal or ground wire, or connector not fully seated
Water intrusion and corroded pins in a connector of the sensor circuit
Sensor B element open
Signal wire shorted to a voltage source

Symptoms

  • Hybrid or EV system warning with MIL
  • Coolant temperature for sensor B shown at about −40 °C in live data
  • Power reduced as a precaution

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 bwiring harnesshybrid control module

Related codes

P2B22P2B20P2B21P2B27P0CF1

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