For over a year, our 2013 GL550 has had a loud buzzing noise coming from the front right (US passenger) side. Usually happens when the car is cold started - always goes away. I plugged in scanning equipment, pulled the codes... found it was AIRMATIC components. In the video, follow along as I replace the valve distribution block (212-320-03-58) and the AIRMATIC compressor (old part was 166-320-02-04; new Arnott part is P-3268). Typically, I'll only use genuine Mercedes-Benz parts on our cars. But Arnott makes a great product and I've been using their parts in our cars for years. They're typically in stock at AutoZone too- so no waiting for a part to come in. You can pick it up today