its saying its seeing the circuit for the LPG injector opened up

thats a nissan engine and harness
check the plug and fuse AT the lpg injector especially where the wire goes in the connector, sometimes the copper breaks in the insulation and the connection will be intermittent
check that
also
clean the connectors with non-conductive electrical parts cleaner

if some1 power washed the unit id suspect dirty connectors

also the year of the engine (theres a sticker on the valve cover) is important if its tier2 or tier3