Hi Guys
I 've been suffering with EGT problems these past few days.
Given the original poster's error I would first check wiring to the G235 and check/clean the earth points under the battery and make sure the pins in the connector are tight and make a good contact. Try and trace the braided cable all the way to the turbo to ensure it's not damaged or restricted.
My current problem is I was hitting the EGT limit (Exhaust gas temperature control bank 1 limit attained) way too often so myself and JBS decided the EGT sensor (G235) could be to blame, I had changed it only about 2 years ago and it cost £170, it fixed my problem at that time (17863 - Exhaust Gas Temp Sensor 1 (G235): Implausible Signal) but I was pee'd off that it could be causing my current problems, so I had to eliminate it and as you say there are hard to find secondhand so I went to TPS and brought one.
Current price is £171 inc VAT, despite having contacts in the trade I could get nothing off it, they really don't make a lot on these.
So I replaced it and it made no difference, temps were still as before, not happy. Started to think the k04 hybrid I have was the problem but then looked at blocked or collapsed cat/backbox and found a small leak on the downpipe to cat flange, so I'm pretty sure my problem with high temps was due to a leak in the exhaust, as when fixed temps are lower, I'm keeping an very close eye on things at the mo.
I will be putting my old one on ebay soonish, not sure of what price I should be asking, but will let you know if you're interested.
This is my old one, brought in 2009, manufactured in 2007. Part number ends with B.
This is the new one, note the D on the part number.
Regards
Jimbo