Powertrain, generic (extended)

P2BB9 Engine Coolant Temperature Sensor 6 Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

A high signal from coolant sensor 6 corresponds to a resistance so large that only an interrupted circuit, a disconnected plug or a wire shorted to a voltage source explains it; read as temperature it would be colder than −60 °C. GM's tables check for this once the engine has run more than 10 s or intake air is warmer than −20 °C. For the sixth-sensor channel the limit is about 298 kΩ in the 2019 L3B/common edition (19OBDG03D) and about 174 kΩ in 2025 (25OBDG03B); 5 s of failures within 6 s give a Type B fault with the MIL on the second trip. As with P2B2E, GM's row names the radiator sensor while the low fault is tied to sensor 6. Bulletin 21-NA-149 lists P2BB9 for chafed harnesses on 2019–2021 pickups. The grounded counterpart is P2BB8.

Likely causes

Sensor 6 connector unplugged or not latched
Broken signal or ground wire, or signal shorted to voltage
Open sensor element

Symptoms

  • MIL on after the second trip
  • Sensor 6 shows about −40 °C or lower
  • Fans may run continuously

Repair estimate

DifficultyMediumDIY possible
Parts and labour€30–350
Time0.5–2.5 h

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

Parts involved

engine coolant temperature sensor 6wiring harnessecm

Related codes

P2BB8P2BB6P2BB7P2B2EP2AFFP01E6

References: gsi.ext.gm.com, gsi.ext.gm.com, static.nhtsa.gov.