boost pressure sensor

docstork · Post by **docstork** » 26 Jun 2013, 11:02

I have a 2001 C70 with 125000 miles. Just the other day the check engine light came on while on the highway. For some time after that I noticed occasional surges at speed (eg 2000 rpm). I checked the fuel cap (a bad cap led to the check engine light 5 years ago) and it was fine. Now the engine runs fine (NO idling issues, NO starting issues) but the CEL is persistent.

I finally got the OBD2 checked this morning (unfortunately, no, I do not own a reader) and it returned codes 236 and 237. So far from my research this combination seems to most indicate a bad boost pressure sensor (photo attached).

First, am I right? Are there other likely culprits? Is there any simple way to test the sensor?

Second, are there any risks to my replacing this myself? The location on this engine is very accessible, and only two torque screws stand in my way. After recently investing a lot of money in new brakes and new tires, I really want to avoid a $200+ mechanic bill if I can.

Third, if replaced, will the codes and engine light clear themselves after enough driving, or am I forced to use a code reader to clear it?

Thanks for any insight and advice.

Post by **jblackburn** » 26 Jun 2013, 12:23

A bad MAP sensor is possible...but I'd start at the turbo control valve vacuum lines first. The valve is attached to the back/left side of the air filter box. Follow each of the 3 vacuum lines to the turbo, inspecting them for splits or cracks at both ends.

Post by **erikv11** » 26 Jun 2013, 13:04

Not sure about your 2001, but for the cars in this forum you can always reset the engine codes and the light (CEL) by just unhooking the battery.

Post by **abscate** » 26 Jun 2013, 19:15

The MAP sensor on the Electronic Throttle Body (ETB) cars lives down on the ETB horn in front of the engine. Its the one nearest the passenger side. It is a delicate little beast of a sensor on a long thin wire - be careful removing it and inspecting it. Sometimes the damage is obvious, which confirms the diagnosis. Before removing it though, try removing the cleaning the electrical connector - which will give the same codes if they get dirty.