2002 MG TF 160vvc Air Intake Temp Fault

Hi all,I'm currently restoring a 2002 MG TF 160 VVC that has been stood in a barn for the last 10 years. It's starting and driving now that I've sorted the brakes, but I'm battling a persistent engine management light and a couple of pending OBD codes ahead of its P0110 (Intake Air Temperature Circuit Malfunction). On the live data, the intake air temperature is locked solid at 140°C.Crucially, it still reads 140°C even when the MAP/IAT sensor (MHK100820) is completely disconnected.Because of this, I'm assuming I have a wiring short-to-ground or the two signal wires are shorted together somewhere in the loom, forcing the ECU to see zero resistance. I've inspected the exposed wires right at the 4-pin plug plug and they look okay, but the loom disappears behind the plenum where it's incredibly difficult to see or , this 140°C reading is confusing the ECU's fueling calculations, and it has now started throwing a pending P0170 (Fuel Trim Bank 1) , or specific pins at the ECU I should test for continuity to isolate the break?Any pointers on how to trace and fix this would be massively appreciated, as it's bound to fail the MOT emissions test while it's fueling for a boiling intake!Thanks in advance,Ben