No spark Volvo 850

Hello, last week my Volvo stopped at a traffic light. Suddenly the engine went off and did not start again. The called ADAC looked for the error but could not find anything. The only thing that could be told to me was that no ignition spark comes. He also checked all fuses, but they were fine. The ignition coil is new. The ADAC had the assumption that it was the crankshaft sensor. In the workshop it was then changed – but without E rfolg. My “screw” no longer has an idea after he has tried out a lot. I then drove to a “Sweden workshop” for error reading. No error is shown. Since the car also has a gas system, I am a specialist for gas systems and have described the problem to him. He says that it can not be the gas system, because the car always starts on petrol and when no ignition spark comes, it can not be on the gas system. Does anyone still have an idea or would really be grateful for any idea, because I would like to drive the Volvo for a few more years.