2009 Mercedes-Benz CLS
Key Replacement - Save vs Dealer in Ventura County

2009 Mercedes-Benz CLS Replacement - Fast, Affordable & Professional

Got a call from a guy over in the Westside neighborhood in Ventura. His 2009 CLS550 was parked in his driveway and the key wouldn't turn in the ignition. Totally locked up. He had already tried his spare key, same thing. So he figured both keys were dead.

I pulled up and tested the remotes first. Lock, unlock, trunk, panic. All four buttons on both keys worked fine. That told me the keys themselves were alive. The problem was upstream.

Plugged into the OBD port and talked to the EIS module. Sure enough, the NEC processor inside had started dropping communication with the key's infrared signal on the ignition side. The module would see the key mechanically but wouldn't authenticate it for start. Classic W219 EIS failure pattern. Forums are full of it. Guys on MBWorld posting the same story over and over: "key won't turn," "steering lock stuck," "tried both keys."

I repaired the EIS on site, re-synced both of his existing keys, and verified the electronic steering lock (ESL) was releasing clean on each start cycle. Took a little over an hour total.

He had already called the dealer before me. They told him to tow it in, leave it, and wait for a diagnosis appointment. He would have been without the car for days minimum. Instead he drove it to dinner that night.

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