What it means
The control circuit of alternative fuel tank shutoff valve C reports a control circuit low condition. Tank isolation cannot be commanded as expected on multi-tank CNG/LPG systems.
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
In a multi-tank CNG or LPG system, shutoff valve C is electrically operated so the vehicle can isolate its tank. The control module monitors valve C's control circuit while commanding it. This code sets when the circuit signal is lower than expected, which can happen if the wire is grounded or the coil or connector is faulty.
Common causes
Most likely first.
- Control wire shorted to ground
- Internal short in valve coil
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine light
- Alternative-fuel warning light
- Difficulty switching fuel modes
How to diagnose it
- Use a scan tool to record freeze-frame data and check whether the fault returns during a command to operate valve C.
- Inspect valve C's connector and harness for corrosion, damaged insulation, loose terminals, or wiring touching ground.
- With the system disabled as specified by the manufacturer, check valve C's coil and circuit for a short to ground.
- Measure the coil and circuit against the manufacturer's specification to distinguish a shorted coil from a harness fault.
- If wiring and coil checks pass, use the vehicle's approved test procedure to assess the control-module output.
Common fixes
- Clean and secure corroded or loose valve C connector terminals.
- Repair control wiring shorted to ground.
- Replace valve C if its coil is internally shorted.
- Repair the control-module circuit if testing confirms an output fault.
Can I keep driving?
Avoid relying on fuel-mode switching or tank isolation while this fault is active; use only the fuel mode the vehicle indicates is available. If the alternative-fuel warning appears or switching becomes unreliable, stop using that fuel system and have the fault checked promptly.
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.