P2B6DEngine Coolant Flow Control Valve Position Sensor Circuit Intermittent/Erratic
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P2B6D covers a position signal from the engine coolant flow control valve that drops out or jumps for short moments, even though single readings may still lie inside the valid window. This exact code appears in no public manufacturer document. In GM's 3.0 L Duramax diesel the valve sends its angle digitally via SENT; the engine computer tests that sensor for a low reading (P2B5E, under 2 %), a high reading (P2B5F, over 98 %) and plausibility (P2B60, more than 12 % deviation) and treats lost SENT communication as a separate fault, but names no intermittent code. A system using P2B6D would count unstable readings, for instance from a loose terminal, fretting corrosion or a harness that moves with the engine. Input faults of this kind must be caught according to CARB 13 CCR 1968.2 (e)(15). Coolant flow control becomes unreliable.
- What you may notice
- Warning lamp, code often stored as intermittent
- Temperature display or warm-up behaviour fluctuates
- Likely causes
- LikelyLoose or widened terminal in the valve connector
- PossibleFretting corrosion on the signal or reference pins
- PossibleHarness rubbing or flexing with engine movement
- RarePosition sensor inside the valve unstable
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €50 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.