Okay, the Intake Air Temperature sensor is part of a multi component sensor, it has a MAP (manifold absolute pressure), MAF (mass air flow) and the Air intake temperature sensor all in one. It's a 4-wire sensor near the throttle body. Do you have a scan tool that can read live engine data? If not, we can do some voltage checks at the sensor itself, it's pretty straight forward verifying the IAT sensor has the correct 5volt feed. It's just a matter of unplugging the sensor and turning the key on, engine off and touch one of the pins on the connector with the other meter lead on Battery Negative post. If you're okay with testing, you don't want to replace a possibly very expensive computer just to find out its a shorted wiring issue.
When you unplug the sensor connector, testing is diagrams 2, 3, 4, 5, 6. With the Key On, engine Off just check for the 5volt Reference feed first on the green wire of the 4-pin connector. You can use pin 4 (black wire) for a Ground if you want, or Battery Negative.
Since no other codes have set for that sensor, I think the Ground for it should be ok. If the 5volts is missing, that is a concern, and we will have to go to the PCM and check the connector for any corrosion. That might also be causing the U code.
Now if you want to go right to the PCM and check the connector for any corrosion or pin issues you can do that first too. You might find that is the root cause here for the other issues, diagrams 7, 8, 9, 10 are the PCM location and the connector C44-K which is the larger of the two connectors, You don't need to remove the PCM or anything, you can make sure the key is off, doors are closed, and disconnect that one connector and check it for corrosion.
Check that MAP sensor connector first for 5volts, it's also possible since the PCM U and P code are showing up after things get heated up, it can definitely be a PCM connector issue or solder joint. Considering where the PCM is located. I don't know why they keep them is location where they're prone to failure.
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Thursday, June 8th, 2023 AT 12:07 PM