Powertrain, generic (extended)

P2B2B Engine Coolant Temperature Sensor 5 Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

Engines with split cooling, electric pumps or separate head, block, radiator and heater branches can carry five or more coolant sensors; the numbering is the maker's choice. P2B2B is the generic circuit code for number 5, meant for controllers that do not separate low from high. No manufacturer documents a set condition for P2B2B publicly. GM does use a fifth coolant sensor input, for instance in its 2019 tables for the 2.7 L L3B and in its 2025 engine tables, but reports its circuit faults only as P2B2D and P2B2E. NTN-SNR lists P2B2B as an electrical fault in the sensor 5 circuit, and CARB requires coolant temperature inputs to be monitored for opens and for readings outside their range. Typical reasons are a loose plug, a broken lead or a failed NTC element.

Likely causes

Loose connector or broken lead at sensor 5
Failed NTC element in sensor 5
Faulty sensor input in the engine control module

Symptoms

  • MIL with stored code
  • Cooling fans or thermal management running on default values

Repair estimate

DifficultyEasyDIY possible
Parts and labour€30–250
Time0.3–1.5 h

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

Parts involved

engine coolant temperature sensor 5wiring harnessecm

Related codes

P2B2CP2B2DP2B2EP2BB5P2AFCP2182

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