What it means
Fuel mode switch signal jumps or drops out — worn contact or vibration. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
How it works
The fuel-mode select switch sends a signal that the control module monitors for a stable driver request. This code sets when the signal jumps or drops out intermittently, which can result from worn switch contacts, a loose connector, or wiring disturbed by vibration.
Common causes
Most likely first.
- Worn switch contact
- Connector with intermittent contact under vibration
- Harness routed against vibrating component
Symptoms
- Check-engine light may come on
- Fuel-mode indicator may flicker or change unexpectedly
- Fuel-mode switching may be intermittent or unavailable
How to diagnose it
- Record freeze-frame data and watch the fuel-mode switch input on a scan tool while operating the switch to look for unexpected changes.
- Inspect the switch connector and harness for looseness, corrosion, chafing, and routing against vibrating parts.
- With the vehicle safely stationary, gently move the harness and connector while watching whether the input drops out.
- Check terminal fit and continuity through the switch circuit while reproducing the intermittent fault.
- Compare switch and circuit behavior with the manufacturer's specification before replacing parts.
Common fixes
- Secure or reroute harness sections that vibrate or rub against nearby parts.
- Repair loose, corroded, or damaged connector terminals.
- Repair intermittent wiring breaks in the fuel-mode switch circuit.
- Replace the switch if its contacts drop out during testing.
Can I keep driving?
If the engine runs steadily on its current fuel, drive cautiously but expect fuel-mode changes to be unreliable. Stop if the engine stumbles or power cuts out, as an unstable request or changeover can disrupt fuel delivery.
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.