What it means
The control module monitors whether tank select valve C responds as commanded to select the alternative fuel tank. It sets this code when the valve’s operation does not match the expected response.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
- The engine or gearbox may go into limp mode
How it works
Alternative-fuel systems can use valve C to route fuel from the selected tank. The module commands valve C and monitors the resulting response; this code sets when valve C does not follow the command, for example because it remains stuck in its last position or its coil no longer moves it effectively.
Common causes
Most likely first.
- Valve stuck in last commanded position
- Coil force degraded
Symptoms
- Check-engine or alternative-fuel system warning light, if equipped
- Difficulty switching fuel tanks
- Loss of power or stalling
How to diagnose it
- Check freeze-frame and live data to identify the requested tank and whether valve C’s response differed at the time the code set.
- Inspect valve C and its connector for contamination, physical damage, binding, or harness strain.
- Use a supported scan-tool output test to command valve C and watch for a change in tank-selection or fuel-system data.
- Test valve C’s wiring, connector contacts, and coil for continuity or shorts using the vehicle wiring diagram.
- If electrical checks pass, investigate mechanical sticking or weak valve movement using the manufacturer’s procedure.
Common fixes
- Repair a loose, damaged, or contaminated valve C connector or wiring.
- Free or replace valve C if it sticks or binds.
- Replace valve C if its coil or mechanical action has weakened.
- Clear the code and verify valve C responds to repeated commands.
Can I keep driving?
If valve C cannot route fuel as commanded, power loss or stalling may result. Keep trips short only if the vehicle runs normally, and avoid relying on tank switching until the fault is fixed.
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.