Code P2138 will not go away?

Hello, there are actually 2 TSBs (Technical Bulletins) for this exact issue, sometimes with a code for the APP sensor as well but I'll post both bulletins for you.

These two TSBs are both related to the same condition, having to do with either water or moisture intrusion into the connector that links the Instrument Panel (IP) to the Body Harness, and there's 2 locations focused on. Diagrams 1-3 are the first TSB and 4, 5 are the second TSB, with the 6th diagram being the OEM APP sensor to ECM wiring diagram showing the 2 connectors that are having the issues (X101 and X202). The X202 connector location is the one where I have seen more moisture issues due to door seals, windshield sealing, and other body areas where water intrusion happens. Even just having the driver's window open slightly during rain. But the X202 connector is going to be down by where your left foot would be, behind the kick panel (diagram 7). The corrosion from moisture gets deep inside the connectors and basically grows in there. It can even get up into the wiring insulation which is called wicking. The other connector X101 (diagram 8) is in the front of the vehicle,
I'm assuming the connectors at the APP sensor have been checked multiple times.
But these TSBs refer more to that circuit's signal not making it fully to the ECM, whether is APP signal 1 or 2,
Auto parts stores carry terminal cleaning spray, Deoxit D5 is the absolute best, but I have also used WD40 Terminal cleaning spray. But start checking connectors, there are only the 2 for that APP sensor circuit, so the issue is going to be in one of them.
You can use a water hose over the vehicle with someone inside with a flashlight to help find any water leaks, the TSBs do also mention resealing certain Body, Plenum and Windshield so the issue doesn't happen again. Hopefully this helps.