What it means
The control circuit of alternative fuel tank shutoff valve B reports a control circuit/open 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
On a multi-tank CNG or LPG system, shutoff valve B isolates its associated tank from the fuel supply. The control module monitors the valve B circuit and sets this code when it detects an open circuit, so it may be unable to command or confirm tank isolation.
Common causes
Most likely first.
- Open in valve control wire
- Open valve coil
- Pin pushed back out of connector body
Symptoms
- Check-engine light
- Alternative-fuel warning light
- Difficulty switching fuel modes
How to diagnose it
- Record freeze-frame data and check fuel-mode status and valve B command data to see when the open-circuit fault occurs.
- Inspect valve B's connector for a pushed-back pin, corrosion, poor seating, or wiring damage along the route to the module.
- Check the valve B coil and its wiring for continuity using the manufacturer's procedure and specification.
- Use the wiring diagram to check the valve B control circuit for an open between the valve and control module.
- If the circuit and coil pass, verify the module's valve B command and feedback path using the manufacturer's diagnostic procedure.
Common fixes
- Seat a pushed-back valve B connector pin or secure a loose connector.
- Repair an open or damaged valve B control wire.
- Clean or replace corroded valve B terminals.
- Replace the valve B coil if it is confirmed open.
Can I keep driving?
Use the fuel mode the vehicle can select reliably and avoid trying to force a switch between fuels. If the system cannot isolate or select a tank as expected, stop using the alternative-fuel system and have the fault assessed before continuing on that fuel.
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.