S40 Wont Idle
 

2002 S40 with 225,000 miles made it to work just fine this morning but threw a check engine light and would not idle on the way home. Codes are:
P0508
P0245
P0445
P0031
P0037
P2401
P0505
Car will start and drive but will not idle unless you keep it above 1000 RPM. I used the scanner to try and turn off codes and they will not turn off. However, the interior lights will turn off for just a second when I try to clear the codes. The car has had a bunch of non-authorized Volvo repairs done to it previously and because of the numerous codes, I suspect an electrical issue. I pulled the battery and the tray below it and the ground looks fine. I have not found any obvious problems. Any thoughts, suggestions, ideas?

I googled your codes, and found this post:

http://www.matthewsvolvosite.com/for...hp?f=8&t=26990

The same symptoms as you, and almost the same codes. Read down to the second to last post, the problem was the intake hose/PCB. Worth a check.

I did see that post and was amazed at how similar it was. The one thing that is different is the blown engine sensor 10A fuse. As soon as I turn the ignition on, the fuse blows. Immediately. I suspect a major short somewhere as usually, you get a code or 2 but 7? Tracing the hot wires and grounds tonight. Yippee!

I did see that post and was amazed at how similar it was. The one thing that is different is the blown engine sensor 10A fuse. As soon as I turn the ignition on, the fuse blows. Immediately. I suspect a major short somewhere as usually, you get a code or 2 but 7? Tracing the hot wires and grounds tonight. Yippee!

Looking at a really funky negative cable from the battery. Shows signs of heat/melting. Not sure that this would be the cause but will get fixed anyway.