Twingo 1.2 16V Starts sporadic

Hello, I’m new here and urgently need HELP with my Twingo. The following problem exists: The Twingo starts only sporadically if it runs then without problems until you turn off again if you want to start again it turns but does not attract you then but the plus pole off the battery it starts again (but this does not always work)In the error memory it shows 2 errors at immobilizer and injection problem this is normal but my mechanicker he w The Wfs should first. To bypass or to turn off this was then strangely not possible one did not come into the config. Then also no speed was displayed at the reading he then typed on the OT giver this was however new. After a long time superior he reprogrammed the engine stew and it then ran for a short time until one has pulled back keys (he said the Wfs it is 100% not he had checked them). Since one can not access the Wfs or also no errors solved However, he didn’t recognize the signal he decided that the MSG was defective. Now my questions can be this ????? Do you have an idea what else it could be or did experience with it?? Oh yes the vehicle also has an LPG gas system from BRC. Thank you in advance for your answers!!