Sensors are designated G235 and 6. They are accurate to +- 5C and are kin expensive. Mine was 140 cost plus tax
yours will be closer to 170 plus tax.Failiure will result in reduction of boost done by leaving the boost solenoid off which will allow the boost in the control hose to open the wastegate when it exceeds the spring pressure. This is known as the basic charge pressure and is 3-400 mbar.
By using this system more precise control of the EGT is possible resulting in protection of the manifold and turbo. Temps over 1000c for too long will result in a trip to the stealer for relief of a sizeable wad.
Older systems used to increase the mixture to cool the charge as soon as boost increased, called prophylactic enrichment. This resulted in higher consumtion and more emissions.
By monitoring the temp, the mixture is enriched as and when req, and to the extent req.
Go to word 01 measured value block 112. This shows bank 1 and 2 at 950c. Below the temp is the % increase in mixture to cool the charge.
Boot the car and stay on full boost for ten secs min. These values will increase and it is possible to see the enrichment working.
Later cars with the secondary air system have much more info from the ecu i.e misfire detection.and lower temp readings as in the Bam engine on the TT/S3