I just drove through some standing water and the reduced engine power came on

What engine do you have? 6.0L or 8.1L gas or 6.6L diesel, there are many possible causes including updating to the latest Powertrain Control Module (PCM) calibration, Refer to TSB 06-06-04-042B. We can flash program or diagnose if needed, call 757-456-0722 for more details and let us know if you will need a $10 rental car.