Hi all. My Father has a 57 plate passat 2.0 TDI 170 PD with DPF. Recently the EML came on. I have run a scan with VAG COM (VCDS) and it has reported the following codes.

005213 - Exhaust gas temp sensor 3 (P145D) -006. Frequency 93 times. This did not bring on the EML.
and

009259 - Exhaust gas temperature sensor B1 S3 (P242B). Frequency 4 times. This is the one that brought the EML on.

Could anyone tell me where the sensors are located and how difficult they are to change. A guide / pics / part numbers would be nice if possible.
Also is there anywhere else that I could buy the sensors from or is this main dealer only.

Many thanks in advance for your help.