What it means
The fuel mode select switch is electrically intact, but its state does not match operating conditions — switched to gas while gas tank is empty, or fast toggling. The ECM rejects the request to avoid stalling.
At a glance
- Usually lights the check-engine light
How it works
The fuel-mode select switch requests a change between the fuels available on a bi-fuel vehicle. The control module checks whether that request is stable and conditions for the requested fuel are suitable; this code sets when the switch request conflicts with operating conditions or changes too rapidly to accept safely.
Common causes
Most likely first.
- Fuel-mode switch contact bounce or wear
- Fuel-mode switch operated while conditions for switching are not met
- Fuel-level or fuel-system condition preventing the requested switch
Symptoms
- Check-engine light may come on
- Fuel-mode indicator may flash or change unexpectedly
- Vehicle may reject a fuel-mode change
How to diagnose it
- Record freeze-frame data and check the requested and active fuel modes to see what the vehicle was doing when it rejected the request.
- Check fuel levels and relevant fuel-system warnings for the requested mode, since an unavailable fuel can prevent changeover.
- Operate the switch once under the conditions specified by the vehicle maker and watch whether its status changes steadily on a scan tool.
- Inspect the switch and connector for wear, contamination, looseness, or damage that could cause contact bounce.
- If the switch signal is stable, diagnose fuel-system conditions that inhibit changeover using the manufacturer's procedure.
Common fixes
- Use the fuel-mode switch only when the vehicle's changeover conditions are met.
- Refuel or correct a fuel-system issue that makes the requested fuel unavailable.
- Repair a loose or damaged switch connector.
- Replace a worn fuel-mode select switch if its signal fluctuates during testing.
Can I keep driving?
If the vehicle remains stable on its current fuel, drive cautiously and do not rely on a requested changeover until the cause is found. Stop if the engine stumbles or loses power during a change, because it may not be receiving a usable fuel supply.
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.