Powertrain, generic (extended)

P2BBA Engine Coolant Temperature Sensor 6 Circuit Intermittent/Erratic

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P2BBA catches short dropouts or spikes in the sixth coolant sensor signal that never last long enough to count as a steady low or high fault. GM includes it in its 2019 L3B/common ECM tables (19OBDG03D) and in the 2025 edition (25OBDG03B): based on the last reading and the sensor time constant, the software allows only a limited change per sample, and if the signal leaps past that window for 5 s within 6 s the code is stored as Type B with the MIL on the second trip. The check pauses while P2BB8 or P2BB9 are active. GM bulletin 21-NA-149 lists P2BBA among the codes from chafed engine harnesses on 2019–2021 Silverado and Sierra 1500. Moving the harness during a live-data check usually reveals the spot; replacing the sensor alone rarely helps.

Likely causes

Chafed engine harness with intermittent contact
Loose or corroded terminal at sensor 6 or the ECM
Sensor element with intermittent internal break

Symptoms

  • MIL on after two trips, may go out again
  • Sensor 6 value jumps in live data
  • Other harness-related codes stored at the same time

Repair estimate

DifficultyMediumDIY possible
Parts and labour€30–400
Time0.5–3 h

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

Parts involved

engine coolant temperature sensor 6wiring harnessecm

Related codes

P2BB6P2BB8P2BB9P2BB5P2BB4P01E7

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