I have a S40 with the 2.4 engine that dies when stopping and idling and occasionally in first gear. It does not die in any other gear. As of this morning it finally stopped all together and ill not start at all. I can hear it attempt to fire but will not run. The following codes are coming up on a code reader.

P0301, C3201, P0601, and P0100.

I have read about vacuum leaks on these cars but cannot find any leaks.

Any ideas where to start first?

 

Start with the basics; fuel, air, spark. Check your fuel pressure. Pull a spark plug and check for spark. Check for compression.

The one strange code you have above is the P0601 for a bad PCM (computer). Normally these do not fail so I would clear the trouble codes and then try to get the car running. If the code immediately reappears then I would look for a disconnected electrical harness to the PCM. You would be surprised at how often this type of problem causes many headaches. The harness looks right but it's just not seated all the way. After many miles and bumps the harness works loose just enough to cause a fault. I had a brake warning light on my 2005 doing this until I finally pushed the electrical connector a tad bit and "click", it seated properly. No more light.