Once I encountered a repair case that a VW New Bora engine cannot start occasionally, but the owner cannot solve the problem and came to me. This New Bora is only riding 800 KM, equipped with BWH engine and there is SAFE message on dashboard.
After connecting vehicle, uses VAS 5054A to diagnose, it read out there is fault code 16897 in engine system. the code means that the starting key error. And got start the prevention system fault code B104V31, which implies the key is not signal. And the other system is normal. According to the diagnostic results, I got the issues maybe caused by key or read coil fault; or prevention start system control unit has gone wrong; or circuit fault.
And then after have a check on circuit graph, it is all right. Check with the other key and the issues still there. It is little possible to have the same fault in the other key, so it might be something wrong with prevention start system control unit.
Troubleshoot: replacement of J285 in prevention start system control unit j362, and use VAS 5054A to direct the function of online matching and try key and troubleshoot finally.
Here I am having a special tip that press TARE button to reset dashboard after have J285 changed. If you have any problem with this engine cannot start occasionally, please leave your message here. I am looking forward to share with you.