MAS cooked after rustproofing done?
 

Well last weekend I decided to get my 99 W202 C230K rustproofed for the first time since it never seen the snow and it will now.

A few days later the Check engine came on...car acting the same and just had the codes read today....shows MAS airflow sensor.

My mechanic was guessing the spray from the rustproof got sucked into the intake and now ruined the MAS sensor.

Im going to get a new one tommorow but mostlikely this is true u think?

Well the only problem with that logic is the air filter is in the way. Not to mention why would the car be running as they were spraying it.

Doesn't sound very likely. The air filter should have stopped anything harmful. MAF sensors go bad all the time. If it contained silicone and was injested by the engine then it is likely that the O2 sensors could be damaged too. When replacing the MAF you should also replace the o-ring in the filter housing as well as the air filter.

Code was checked and reset and never came back on after a few hours drive. Car tends to "bog down" slightly when accelerating harder such as getting on the highway and thats about it.....shifts normally etc.

Ya and car was not running when rustproofing was being done but I recall oil mist flying everywhere in the shop and they did spray in the engine bay areas...the intake on the other side where the air goes in is oily but I will take a better look tommorow.