What it means
The control module detects a low signal in the control circuit for alternative-fuel tank shutoff valve A. The cause may be a short to ground or another circuit fault.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Alternative-fuel tank shutoff valve A is controlled through an electrical circuit that operates the valve and helps isolate the tank. The control module sets this code when it detects a lower-than-expected signal in that circuit, which can result from a short to ground or another circuit fault.
Common causes
Most likely first.
- Short to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
Symptoms
- Check-engine light on
- Alternative-fuel system warning
- Reduced or unavailable alternative-fuel operation
How to diagnose it
- Read freeze-frame data and alternative-fuel system codes to see when the low signal at valve A was detected.
- Inspect valve A’s connector and harness for corrosion, damaged terminals, and insulation rubbed through against the chassis or another component.
- Use the wiring diagram to identify the valve A control wire and check it for a short to ground before replacing the valve.
- Check connector terminal condition and circuit continuity for high resistance, following the manufacturer’s test procedure.
- If the wiring and connectors are sound, test valve A and its control module circuit using the manufacturer’s procedure.
Common fixes
- Repair chafed insulation or a control wire shorted to ground.
- Clean corroded valve A connector terminals and restore a secure connection.
- Replace a damaged section of the valve A harness.
- Replace valve A or repair its control module circuit only if testing identifies it as the cause.
Can I keep driving?
The vehicle may still run on another fuel, but alternative-fuel operation may be reduced or unavailable. Have the low circuit signal repaired before relying on the alternative-fuel system.
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.