My car makes a high pitch noise in the first 30-40 sec of the start up. After that it sounds and drives just fine. Not long ago I changed the serpentine belt. Any idea what might be the problem? I also don’t see any fluid leaking. The car is 2010 w212 model with 120,000 km.

thank you.

Holly cow... it's hard to ignore that

I think you can focus on testing your electric AIR INJECTION PUMP more so than serpentine or steering pump.

You can use your handy scanner to control its power ON/OFF.

Unplug connector if you time until your parts arrive.

I know. It is loud, but only short period of time. No other issues including decrease in performance. Subsequent start does not have that issue. No error code code from scan tool. Thanks.

Perfect new year's day fix!

You can use your handy scanner to control pump power ON/OFF.

(Unplugging may bring up a code)

Sounds like someons is cutting wood with a circular saw.

Im guessing your secondary air pump is shot. Disconnect it before the next cold start and see if it goes away.

Thank you.

Yep, that is the secondary air injection motor, which only run during cold start as part of emission reducing strategy.
You wont get error code from a bad bearing of secondary air injection pump of M272 / M273

Does that mean you can just chuck it in the trash?