P23C3Engine Coolant Bypass Valve C Position Sensor Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P23C3 is the general electrical fault on the feedback sensor that tells the engine module how far the third coolant bypass valve has turned. On modern thermal management modules this valve is a motor-driven rotary part, so without a valid angle the module loses its closed-loop positioning. No manufacturer documents P23C3 publicly. GM's 2025 engine tables read the same sensor digitally via SENT and only split it into low and high cases (P23C4, P23C5); a fault that fits neither window would fall under this umbrella code. CARB counts such cooling actuators and their sensors among the monitored comprehensive components. The driver may see slow warm-up, a higher or fluctuating temperature gauge and a warning lamp; motor driver faults are P26B7 to P26B9.
- What you may notice
- Engine warning lamp
- Engine takes longer to reach operating temperature
- Coolant temperature gauge reads unusually high or unsteady
- Likely causes
- LikelyLoose, corroded or coolant-contaminated connector at the valve module
- PossibleDamaged signal, 5 V reference or ground wire of the position sensor
- PossibleInternal failure of the position sensor built into the valve actuator
- RareFaulty sensor input or reference supply 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
- Medium · Usually a job for a workshop.Typical cost: €60 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.