[NMKawierider]

Not possible for water to enter the exhaust...at least that far while running. But at that level where the exhaust tip is...there is lots of things that would be under water including most all the electronics of the engine control systems like fuel injectors,iac valve, TPS, both O2 sensors, spark plugs...maybe coils as well. I'd keep looking. Might also double-check the air box cover seal.

[doug80638]

So you step on the throttle and there is no change in the engine?

Is the throttle a fly-by-wire arrangement on the 2018? If not, the engine should have either stalled or spun up.

If the engine didn't quit or change RPM then it must be fly-by-wire. The water is interfering with the signal to the throttle body control unit, the throttle isn't moving, and the ECU throws a code/light. Remove the water and the interference goes away, the light goes out, and the throttle works.

That's what it sounds like given the current information, but we'd need confirmation that these are indeed fly-by-wire.