P0618: Alternative Fuel Control Module Keep Alive Memory Error
What to do
The vehicle should revert to petrol and remain driveable. On a converted vehicle this is best taken to the installer or a gas conversion specialist rather than a general workshop, since the second system is aftermarket and not covered by manufacturer tooling.
What this code means
The keep-alive memory in an alternative fuel control module has failed its check. Vehicles converted to run on liquefied petroleum gas or compressed natural gas carry a second module managing the gas system alongside the original petrol one, and it maintains its own learned adaptations.
On converted vehicles the quality of the installation matters as much as the equipment, and a permanent supply taken from a poor connection is a frequent cause. The vehicle will normally revert to petrol, which is the designed fallback.
Likely causes
Start here
- Battery disconnected or gone flat · easy
- Poor permanent supply connection · moderate
- Corroded or loose connector · easy
Less common
- Failed alternative fuel control module · specialist
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
Sign in or create an account to add what you found about P0618.