the link I gave..Australia, says the following
What if I can’t get LPG? Or I run out of gas?
Doesn’t matter. You don’t even need to switch the system off. You will notice a decrease in power as the LPG runs out. The system does not affect the diesel injection system, so it will continue to run on diesel as it did before the Diesel/Gas system was fitted, although with noticeably less power! When you do fill up the LPG again, the system will automatically begin injecting gas again.
DIESEL GAS AUSTRALIA