P2BBAEngine Coolant Temperature Sensor 6 Circuit Intermittent/Erratic
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- 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.
- What you may notice
- 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
- Likely causes
- LikelyChafed engine harness with intermittent contact
- LikelyLoose or corroded terminal at sensor 6 or the ECM
- RareSensor element with intermittent internal break
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €30 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.