P2BB9Engine Coolant Temperature Sensor 6 Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- 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.
- What you may notice
- MIL on after the second trip
- Sensor 6 shows about −40 °C or lower
- Fans may run continuously
- Likely causes
- LikelySensor 6 connector unplugged or not latched
- LikelyBroken signal or ground wire, or signal shorted to voltage
- PossibleOpen sensor element
- 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 – €350
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.