Our 2001 S40 1.9T has a reoccurring CEL and Service Light which comes on. A few weeks ago the CEL was illuminated and I found a large hose coming from the throttle body to the radiator was missing, apparently dried out and broke off. Placing my finger in the hole near the throttle body chokes the car out. I replaced this hose and the CEL eventually went off. The car passed emissions. Now the CEL and Service light comes on occassionally. I had the codes read at Auto Zone: P0301, P0302, P0304 (Misfires 1,2 & 4), P0171 and P0101 displayed. I notice a common thread through each error code which is a vacuum leak. On two (P0101 and P0171), also mention MAF faulty. I've cleaned the MAF and it seems to be working fine. I've noticed that some of the small Vacuum hoses are pretty dry and hard so I'm suspecting this is another Vacuum hose which has deteriorated and causing codes to be thrown. My plan is to start off with replacing all the dry vacuum hoses then move on from there, however I'd love to have you Volvo Guru's input on this... Suggestions??? Thank you!!

 

I think you are looking after it pretty well. My 2001 needs regular TLC to keep it going.

 

If you're looking at your map sensor on your intercooler, beside you map sensor there in a plug that looks like a bolt. Does anyone know what that is