P2BB5Engine Coolant Temperature Sensor 5 Circuit Intermittent/Erratic
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P2BB5 is the erratic-signal code for coolant sensor 5. Unlike the hard circuit faults P2B2D and P2B2E, the reading here stays within the valid range but changes faster than the sensor's thermal inertia allows, which betrays a contact that briefly opens or shorts. GM has carried the code in both its 2019 L3B/common tables (19OBDG03D) and its 2025 ECM tables (25OBDG03B) with the same rule: limits for the next sample are calculated from the previous one, and violations for 5 s within a 6 s window store P2BB5 as Type B, MIL after two trips. GM bulletin 21-NA-149 lists it among the codes a chafed engine harness causes on 2019–2021 Silverado and Sierra 1500 pickups. Wiggle-test the harness while watching live data before replacing the sensor.
- What you may notice
- MIL on after the second trip
- Sensor 5 value spikes in live data
- Often stored together with other harness-related codes
- Likely causes
- LikelyChafed engine harness with intermittent contact in the sensor 5 wires
- LikelyLoose, spread or corroded connector terminal
- PossibleSensor element breaking intermittently
- 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.