I recently purchased a 2001 Volvo s40 with 88k miles. After about 200 miles the CEL came on so I gave it a scan, it pulled a P0171 so I decided to go out and get some MAF cleaner and clean it out. After I cleaned the MAF I cleared all the codes and the check engine light went off. Shortly after about 40-50 miles the CEL came on again, scanned it and got a P0236 Turbo/Supercharger sensor code. Unfortunately I have no idea where to even begin with this code lol. Some weird things also have been happening since I got the car. Ive had the car for a month now, Once I first got the car I ran it till it was empty and filled it with super. When I had super in the car it would idle rough on start and jump between 900-1500 RPM and shake a bit till I applied some gas. The car also has stalled twice since I got it. Both times were pulling into a drive thru and each time the oil light would come on. I checked the oil and its perfect, I also topped it off after I got it. If anyone has experienced any of this please fill me in. I plan on switching to synthetic oil and will try premium fuel over regular. I have filled the car once with super and had problems and 4 times with regular and had little to no problems. Any recommendations? Thanks in advance!!

 

Try checking out the MAP sensor ref the P0236 code (this is the mean air pressure sensor, not the mass airflow sensor).. A replacement goes for $80 or so...

 

What ended up being the problem here? I'm having the same exact problem and the same exact code (p0236). I've recently replaced the MAP sensor when I got a MAP specific error code.

 

My son's 01 S40 had the same code and the P0237 I believe. You may have 1 or 2 boost pressure sensors depending on if it is an early 01 or late 01. If it has 2, one is on the intake manifold, and the other is on the top of the inter-cooler. They are the same. I tried changing the one on the intake manifold, cleared the code but it came back. Then I reinstalled the old one and put the new one on the inter-cooler and all was good. By the way, buy the Bosch sensor. It is the same as Volvo uses. Others have reported problems with other off brands.

 

Hello, The problem was the MAP sensor, they are about $50 shipped on amazon I used the bosch ones. There is one on the radiator hose and one on the front by the fuel injectors, you have to take the cover off to reach it. After I replaced both of them my car boosted again and had plenty of power. Hope this helps!