So i bought myself a Volvo S40 2003 1.8(the one without turbo) with 340k km on it(Was a 1 person owner and was maintained) And it has been driving beautifully, such a good car!
No problems at all so far, but out of the blue it all just got weird.

I was with friends driving around all good, then i leave in my car to go home and i stop at a local supermarket to get some soda and when i get back in my car it wont start. Just cranks and might once in a while start and get to 500 rpm and die again.

My friend works at Volvo as a trainee and he scanned my car and it reported a failure on the camshaft sensor and we got it swapped the next day with a Volvo Original part and it drove again the same day like it always had.

Fastforward to the next day and im going for a drive and it starts all over, but this time no OBD codes not even with a professional Volvo scanner...
Still the same cranking, sometimes starts but dies in 2 seconds.

I've charged the battery, checked the voltage on the cable to the camshaft sensor and it's fine(5volts), tank is full, max oil and so on..

I get no immobilizer lights or anything. Oil lights shuts off when i crank - batterylight does not but i dont think it shuts off before the car is really on
Really no indication of something being wrong...

Does any of you have any idea of what is wrong? I can't really wrap my head around it...

 

It's a tough one, since there are SO many things that can cause the problem.

I'm a simple guy, so my suggestion is to get a can of starter "fluid" and shoot some into the air cleaner and see if it starts up - temporarily - immediately. If it does, you've just diagnosed it as a fuel problem. If it doesn't, you're looking at spark or electronics (and there are a host of things that could cause intermittent starting).