P23C6Engine Coolant Bypass Valve C Control Circuit Driver Current/Temperature Too High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P23C6 is set by the output stage itself: the H-bridge that drives the motor of coolant bypass valve C reports more current, or more heat, than it can tolerate. GM labels it a motor overcurrent in two 2025 summaries, the diesel table 25OBDG04B (3.0L Duramax) and the gasoline table 25OBDG03B; the driver flags it while energized, with a controller-specific trip point listed between 8.1 and 12.8 A, and the code matures after 2 seconds within 5 seconds as Type B. Typical triggers are a seized valve rotor, a motor with shorted windings or a partial short in the motor wires. To protect itself the driver switches off, so the valve stays where it is. Open and shorted motor circuits are P26B7 to P26B9.
- What you may notice
- Engine warning lamp after two trips
- Bypass valve C no longer moves and stays in its last position
- Engine runs too cold or too warm depending on where the valve stopped
- Likely causes
- LikelyValve rotor stiff or seized by deposits or worn seals, so the motor stalls
- PossibleShorted windings in the valve motor drawing excess current
- PossibleMotor wires partly shorted to each other or to ground
- RareOverheated or faulty H-bridge driver in the engine control module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €150 – €1,100
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.