Volvo Repair: stalling, no Idle, mass air flow, air control valve

Question
There was no Fuse for engine sensors under hood. And there were no blown fuses of all that are there. But there was a vac pump fuse that was not in place. Should there be a fuse there? or is it some option?

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Followup To

Question -
A friend has a 2000 S40 1.9L turbo. Reciently it was run low on fuel and after that would not idle. Engine light has been on for quite some time I was told. She does not have the money totake it to a dealer for repairs. I do repair work on the side. A former mechanic. I replaced her fuel filter first to no avail. To get the car to start and stay running  you must keep your foot on the gas peddal. if you let off it will stall. I pulled the codes and found P0128,P0455,P0420,P0102, P0107. I was told by someone that has some exp. with volvos that there is a problem with the wireing harness in the eng comp. check connectors and grounds. if nothing then Mass air Flow should be replaced. Any Ideas?

Thanks Tim

Answer -
The fuse in the engine compartment for "engine sensors" is most likely blown.  The crankcase breather on the intake tube shorts out all the time and causes it to blow.  You will see a sensor on the intake tube between the air filter and the turbo charger near the bottom.  Reach down there and disconnect it.  Replace the blown fuse and it should run.  The sensor is only available with the whole tube however and that tube is 70-100 dollars depending on year, engine, etc..  Its a fairly common problem and I feel pretty confident saying thats it.  If the fuse isn't blown then your most likely problem is the idle air control valve on the front of the throttle body.  Not as common but we do see that too.

James

Answer
The vacuum pump design for 2000 models changed.  There was a recall to replace them all with new designs so yours no longer uses the original locations for the fuses/relays etc.  If you still have the original design pump then yes it should have a fuse there otherwise I don't think its an issue.  I will have to look at a 2000 s40 when one comes in to look over for something else that could be causing your problem.

James