engine stalls after starting when it's been raining

[vratnik]

When it rains, or after rain, I encounter an issue where the engine shuts off shortly after ignition. Typically, upon starting, the RPM climbs to around 1000 and returns to 400 but this time it then unexpectedly fell to zero, rather than maintaining the usual 400. To keep the engine running, I find myself having to press the gas pedal halfway down. Then, while simultaneously pressing the brake, I shift into drive and ease off the brake to get moving. The RPM stabilizes after driving for approximately one kilometer, no longer plummeting as before. This problem seems to occur exclusively during adverse weather conditions, such as rain or high humidity following rainfall. Despite cleaning the throttle body and MAF sensor, the issue persists.
Sometimes also "Service ESP system" and "Hill hold disable" messages pop up during this.

[KuroNekko]

I experienced this same issue after washing my engine bay a few times (without too much water and mostly on the block) and believe the culprit might be the MAF sensor. I believe the moisture is causing a malfunction. The cure is typically disconnecting the battery after the components have dried out completely. I am now more careful when washing the engine bay and will cover up the MAF sensor with a plastic bag or wrap. I also think it's a good idea to idle afterwards and let the engine heat dry things up.

As for the rain issue, it's a bit tricky but check to see how well your MAF sensor is sealed onto the intake tubing. I find that one of my screws is a bit loose despite tightening it. This might be why moisture is getting in and disrupting the MAF. However, I have no issues in rain.

Of course, I'm not a pro and don't know if this is the actual cause but it's my main suspicion after having this issue a few times, right after an engine wash.