Volvo: 1999 Volvo P0236&P0237 Fault Codes, signal cable, pressure sensor

Question
I have 1999 Volvo and now it failed emssions with the following faults: P0236 and P0237? any Idea's on to how much this thing should cost me? or is this something that i can do my self?
I tried seaching this issue, but with no luck, please help..

Thanks

Answer
Fred,
Hopefully you have a S80 PO236 boost pressure sensor. PO237 BOOST PRESSURE SENSOR Condition
If the control module receives a signal from the boost pressure sensor which is lower than 0.2 V (low signal) or higher than 4.85 V (high signal) it is interpreted as a fault and ECM-1600 is stored. Same as PO237

Condition
Boost pressure control runs in an open-loop, in other words set duty cycles are generated regardless of boost pressure.

Possible source

Signal too high:


contact resistance in terminals
short-circuit to supply voltage in the signal cable
open-circuit in signal cable
defective boost pressure sensor
Signal too low:


short-circuit to ground in the signal cable
defective boost pressure sensor
Condition, none