Sounds like the immobilzer is kicking on; when low voltage or the battery is disconncted, the immobilzer can go goofy. Typically, a hard reset of the ecu will clear this up; keep in mind, the charging system and battery, need to be in good working orderoir it can happen again.I wound start with getting the charging system; get it tested, to make sure it is working 100% (alternator, battey are good).
Beyond that, the reprogramming of the key; is something many shops do but when this is done, it typically removes all key programming and adds only the keys, that are present during the key matching process. When rhis is done, typically, each key is added; one by one, any keys not added will not work, the immobilzer will kick on, rhe light in thr speedo cluster will flash and th immo will kill the ignition, the engine will die.
Let us know, what trouble codes you are getting and what parts, have been teplaced so far. What type of shop, is doing the work for you (vw dealer, indepednant shop, etc); it can be challenging to diagnose these issues, having the correct vw type scan tool, can help but even then, it may take multiple tries, to correctly diagnose and successfully, repair a intermittant problem like this.
Simce, you already paid a shop to do the repair work; I would contact them and have rhem check it out, to see what is going on. It is possible, the charging system gets low, the immo gets confused; a aspect of the immo system may not be working or the programming isn't right. Each oart of the system, has to work perfectly together or the ignition will be blocked by the immobilizer, resulting in a no start condition.
Here are some links; to understand, how the immo system works:
Beyond that, the reprogramming of the key; is something many shops do but when this is done, it typically removes all key programming and adds only the keys, that are present during the key matching process. When rhis is done, typically, each key is added; one by one, any keys not added will not work, the immobilzer will kick on, rhe light in thr speedo cluster will flash and th immo will kill the ignition, the engine will die.
Let us know, what trouble codes you are getting and what parts, have been teplaced so far. What type of shop, is doing the work for you (vw dealer, indepednant shop, etc); it can be challenging to diagnose these issues, having the correct vw type scan tool, can help but even then, it may take multiple tries, to correctly diagnose and successfully, repair a intermittant problem like this.
Simce, you already paid a shop to do the repair work; I would contact them and have rhem check it out, to see what is going on. It is possible, the charging system gets low, the immo gets confused; a aspect of the immo system may not be working or the programming isn't right. Each oart of the system, has to work perfectly together or the ignition will be blocked by the immobilizer, resulting in a no start condition.
Here are some links; to understand, how the immo system works:
