P23C6 code meaning
Engine Coolant Bypass Valve C Control Circuit Driver Current/Temperature Too High
Powertrain system Generic code P23xx codes Check engine light
What P23C6 means
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.
P23C6 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P23C6
- 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
Common causes of P23C6
- Most 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
- Less likelyOverheated or faulty H-bridge driver in the engine control module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Coolant bypass valve c
What each part of P23C6 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 3 | Area: ignition system or misfire. |
| C6 | The exact fault in that area. |
What to do next
- Note P23C6 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P23C6
What does P23C6 mean?
P23C6 means "Engine Coolant Bypass Valve C Control Circuit Driver Current/Temperature Too High". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P23C6?
Drive gently and only to a workshop. With P23C6 the car can go into limp mode (reduced power) to protect itself.
Will P23C6 fail an emissions test?
Yes, it can. P23C6 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P23C6 to fix?
Difficulty: hard. A typical repair takes 1 to 4 hours of work. This is a job for a workshop.
Will P23C6 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.