The green circled area is exactly what I was referring to
Just a thought, but maybe the reason for the code 26 is because you don't have the air intake temperature sensor hooked up. Is there a black two-wire harness connector in that vicinity?
If so it might suggest that the sensor may have indeed been in that location but for some reason may have been removed, which if that were the case, leads me to wonder why didn't the code show up earlier.
With regards to redwagon's suggestion, as far as I was aware I didn't think that the air temperature sensor was incorporated into the MAP, I thought that they were separate, but anyway we are all here to learn and help each other out.
What I typed above are just my suggestions and you can keep us informed UK_SPORT.