What it means
Voltage on the third coolant bypass valve control line is below the expected window. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
How it works
Coolant bypass valve C is controlled through an electrical line monitored by the engine control module. This code means the voltage on that control line is below the expected range, which can result from a short to ground, a shorted valve solenoid, or poor connector contact.
Common causes
Most likely first.
- Control wire shorted to ground
- Internal short in solenoid coil
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine light
- Engine temperature may fluctuate
- Heating or warm-up may be affected
How to diagnose it
- Review freeze-frame data and live coolant-temperature readings, and confirm whether the valve C control fault is present now.
- Inspect valve C's connector seals and pins for water, corrosion, pushed-back contacts, or poor seating.
- Inspect the valve C harness for chafing or damage that could let the control wire contact ground.
- With the circuit safely isolated as specified by the manufacturer, test the valve C solenoid for an internal short.
- Measure the control-line condition and check for a short to ground while moving the harness gently to locate an intermittent fault.
Common fixes
- Dry and clean corroded valve C connector contacts, then repair any damaged seals or pins.
- Repair chafed or grounded control wiring to valve C.
- Replace valve C if its solenoid is internally shorted.
- Repair the control module circuit only after wiring and the solenoid test correctly.
Can I keep driving?
If the temperature gauge stays normal, limit driving to short trips and keep monitoring it. Stop if the engine overheats or temperature changes abruptly; the low control-line fault can prevent valve C from regulating coolant flow.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.