Volvo s40 2.4 2007. New here and I’m desperate for help. The car was throwing the code for the CTS so in order to change that I had to move the intake and disconnect the ecm. Put everything back together and went to start it and now it just cranks and won’t start. I hooked up the scanner and the scanner is throwing a code for the crankshaft position sensor. Can that go bad that suddenly? Prior to the CTS it would idle really rough and sometimes stall until heated up then would smooth out. The plugs and coil packs are new. I’ve replaced the MAFS also. I did triple check that everything was hooked up properly. Am I doing something wrong? Is there a reset I need to do for the computer or something? I can also hear the fuel pump priming. PLEASE HELP.

 

Your previous problem could have also been the CPS. They're notorious for that kind of behavior (intermittent or thermal). I'd say the smart play is to swap it out and see if it fixes your issue. Not that spendy, IIRC...

 

will try that and update after! I just don’t understand why it was running and now all the sudden won’t. Can the sensor just die like that?

 

I got it started. Now it’s throwing a code for p0607 and it has a rough idle at start up but once it warms up. It evens out. I read that it could be the computer? Thoughts?

 

This is where it would be good to have a laptop loaded with VIDA, or at least some sort of Volvo-specific two-way scanner. You should be able to get a lot more detail about the failure than just the generic OBD code.

And of course, it makes sense to double-check the connection at the ECM (since disconnecting / reconnecting it coincides with the onset of the issue).

 

habbyguy, hopefully you’ll have a second to look at all of these and see if you see a common issue or something that I can check. Thank you!

 

I'm not up to speed on a lot of those variables, but all the missing CAN signals points to a problem somewhere in the "digital backbone" of your car. With those signals not present, lots of things can and will go wrong. I have zero experience troubleshooting these in a Volvo, so can't be much help - I do know that you'll probably need an oscilloscope to troubleshoot the system, but can only suggest you search on the error codes and descriptions for those "missing signal codes" to see if you can find something actionable.

Again, if you had a working VIDA system hooked up, it would probably point you in the right direction, so it might be a good play to check into getting a laptop loaded with the software and getting your hands on the appropriate cable(s).

 

My brother in law owns an auto electric shop and he suggested checking the ground. So I made a temporary ground and I waited about 10 minutes, started it, and all the messages and warning lights were gone and it idled normal. Unplugged the make shift ground and the lights came back. Looked under the car and the ground wire bolt is rounded off and the connection to the engine block is all corroded. Going to get wire tomorrow and make my own ground. I’ll let you know if that’s the final solution!

 

It all makes sense - hope your fix holds (when you do the "final fix" for that flaky ground strap).