What it means
The disable feedback signal sits above its valid window. Typical cause is a short to battery on the feedback wire or a failed pull-up in the input stage.
At a glance
- Usually lights the check-engine light
How it works
The alternative-fuel disable signal circuit returns feedback that confirms the disable command was carried out. The control module sets this code when the feedback voltage is above its valid range, which can result from a battery-power short or a fault in the module's input pull-up circuit.
Common causes
Most likely first.
- Feedback wire shorted to a B+ supply
- Pull-up resistor in the input stage failed
- Connector pins corroded - high contact resistance
Symptoms
- Alternative-fuel operation may be unavailable
- Engine may switch to or remain on the other fuel
How to diagnose it
- Use a scan tool to record freeze-frame data and view the disable feedback value alongside the command status.
- Inspect the feedback wire and its connectors for damaged insulation, pinched sections, or contact with a battery-power supply.
- Check connector terminals at the relay and module for corrosion, looseness, or poor contact.
- With the circuit isolated as specified by the manufacturer, test the feedback wire for a short to battery voltage.
- If the wire and connections are sound, use the manufacturer's procedure to check the module input pull-up circuit.
Common fixes
- Repair feedback wiring shorted to a battery-power supply.
- Clean or repair corroded or loose connector terminals.
- Repair damaged or open sections of the feedback wire.
- Replace or repair the control module if its input pull-up circuit is confirmed faulty.
Can I keep driving?
The system may not verify that alternative fuel has been disabled, so operation on that fuel may be unavailable and the engine may use the other fuel. Avoid relying on the alternative-fuel system until diagnosed; stop if fuel leakage or unsafe engine behavior occurs.
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.