What it means
Voltage on the alternative-fuel disable control line is above the expected window. Often a short to battery upstream of the relay or a stuck-on driver in the control module.
At a glance
- Usually lights the check-engine light
How it works
The alternative-fuel disable control circuit carries the command used to disable that fuel system, often when the engine switches to another fuel. The control module monitors the command line and sets this code when its voltage is higher than the allowed range, which can happen if the wire is connected to battery power or the module output stays on.
Common causes
Most likely first.
- Disable control wire shorted to a B+ supply
- Output driver stuck on inside the control module
- 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 check the alternative-fuel disable command and circuit status to see when the high reading occurs.
- With the ignition off, inspect the disable-control wiring and connectors for damage, corrosion, or contact with a battery-power wire.
- Check the connector pins for corrosion, looseness, or poor contact that could distort the control-line reading.
- With the circuit isolated as specified by the manufacturer, test the disable-control wire for a short to battery voltage.
- If the wiring and connections are sound, use the manufacturer's procedure to assess the control-module output driver.
Common fixes
- Repair damaged wiring that is shorted to a battery-power supply.
- Clean or repair corroded or loose connector terminals.
- Repair an open or damaged section of the disable-control wire.
- Replace or repair the control module if its output driver is confirmed faulty.
Can I keep driving?
The engine may be unable to use the alternative fuel and may switch to or remain on the other fuel. If it runs smoothly and the fuel system is secure, limit driving to what is needed to arrange diagnosis; stop if the engine runs poorly or fuel leakage is present.
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.