Fridge problems

Automatic switch over on my thetford fridge not working (ie) if the fridge is on mains and it is disconnected the gas automatically comes on when you start the engine it goes to 12 volt when you stop the engine the gas comes on and when you plug in the mains the gas goes of but now I have to do it manually and am getting a code 6 any ideas

Is there not a built in delay, when you switch off the engine. I’ll check the book tomorrow.

It’s started to be intermittent when I unhook it from mains the gas will start up straight away put it back on mains leave for awhile unhook again won’t change over to gas the same with the 12 volt side but the gas won’t come on after switching the engine off code error 6 starts flashing you can hear the relays clicking on the pcb ,I can still make it work manually,but I’m the type where I like it to work the way it’s supposed to I can’t stand watch code six flashing 🤪