Powertrain, generic (extended)

P2B22 Hybrid/EV Electronics Coolant Temperature Sensor B Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2B22 says the signal voltage of electronics coolant sensor B has fallen below its valid band. Since these sensors are NTC thermistors, a low voltage would mean an absurdly hot coolant, so the usual explanation is a signal wire touching ground, moisture bridging the connector or an internally shorted element. No manufacturer documents P2B22 publicly; NTN-SNR's catalogue calls it a too-small signal of sensor B. GM's 2019 HPC2 table shows typical numbers for the matching sensor A code P0CF0: below 4 % of the 5 V reference (0.2 V) for 4 s within 5 s, with more than 10.2 V supply, Type B. CARB requires such out-of-range checks on inverter cooling inputs. Because a hot value is taken seriously at first, the pump runs harder and power can be limited. P2B23 is the opposite case.

Likely causes

Sensor B signal wire chafed through and shorted to ground
Water or coolant in the sensor connector
Internally shorted sensor element

Symptoms

  • Warning lamp or hybrid system message
  • Electronics coolant pump and fans running at high output
  • Reduced electric drive or charging power

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 bwiring harnesshybrid control module

Related codes

P2B23P2B20P2B21P2B26P0CF0

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