What it means
General electrical fault on the fuel mode select switch — used on bi-fuel vehicles (CNG/LPG/H2/gasoline) so the driver can pick the active fuel. With the input invalid, the ECM falls back to the default fuel and disables operator-selectable switching.
At a glance
- Usually lights the check-engine light
How it works
On a bi-fuel vehicle, the fuel-mode select switch lets the driver request which supported fuel system to use. The control module monitors the switch circuit, and this code sets when its electrical input is invalid, so the module may stay with its default fuel and disable selectable switching.
Common causes
Most likely first.
- Faulty fuel-mode select switch
- Open or shorted switch wiring
- Loose, corroded, or damaged connector
Symptoms
- Check-engine light may come on
- Fuel-mode indicator may be absent or incorrect
- Vehicle may remain on one fuel or fail to switch fuels
How to diagnose it
- Record freeze-frame data and scan the fuel-mode status and related codes to determine whether the input is missing, fixed, or otherwise invalid.
- Operate the fuel-mode switch and watch its status on a scan tool to see whether the requested state is recognized.
- Inspect the switch, connector, and harness for damage, corrosion, loose terminals, or pin push-back.
- Check switch continuity and circuit wiring for opens or shorts using the vehicle's wiring information.
- Test the switch input and module response against the manufacturer's specification before condemning either component.
Common fixes
- Reconnect or clean a loose or corroded fuel-mode switch connector.
- Repair an open or shorted section of switch wiring.
- Replace a faulty fuel-mode select switch.
- Repair or replace a control module only if circuit tests confirm it is not reading a valid switch input.
Can I keep driving?
If the vehicle runs normally on its default fuel, a short, cautious trip may be possible, but do not count on being able to change fuels. Avoid driving if the selected fuel is running low or the engine stumbles, since a failed changeover could leave the vehicle without usable 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.