troubleshooting

Hi all - I looked at several different posts and didn't see any quite like what I'm experiencing, so here goes - I got caught in VERY heavy rain downpour for about 5-7 minutes a couple of nights ago (I usually don't drive the beast - 2000 black on black E39 M5 - in the rain if I can avoid it)...

Recently installed a Stage 2 Air Intake from AFE on my 2006 BMW M5. Immediately upon starting the car, two fault codes came up and my mechanic has been unable to troubleshoot. Codes are: 1) 2737/2738 - Filling, plausibility (Banks 1 and 2) 2) 2712/2713 - Air-Mass Sensor, plausibility. We...