Mercedes-Benz W212 Ignition Lock Switch A2129055600 - Used Original Parts

Diagnosis and Common Symptoms

From a workshop perspective, failure of the W212 Electronic Ignition Switch (EIS), or ignition lock, is a common and definitive no-start condition. The primary symptom is the complete refusal of the vehicle to acknowledge the key. You'll insert the key, and nothing will happen—no dash lights, no radio, and the steering lock will not disengage.

Intermittent faults can precede total failure, such as the key needing to be inserted multiple times before being recognized. On a diagnostic scanner, you will typically find fault codes stored in the EIS module related to internal hardware failure or communication errors with the Electronic Steering Lock (ESL). Look for codes like A25464 ("The electronic steering lock has a malfunction") or A25408 and A25409, which point directly to an internal fault within the ignition switch itself.

Introduction

This is a genuine Mercedes-Benz Electronic Ignition Switch (EIS), a critical component of the Drive Authorization System (DAS). Sourced directly from a donor vehicle, each unit undergoes a rigorous bench test to verify its core functionality and communication protocols before being made available. Opting for a tested, genuine used part provides a cost-effective solution without compromising the integrity of your vehicle's complex security system.

Product Details

• Brand: Mercedes-Benz

• Model Compatibility: W212 (E-Class, approx. 2010-2016)

• Part Name: Electronic Ignition Switch (EIS) / Ignition Lock

• Condition: Genuine Used (Tested Working)

• Notes: This is a theft-relevant part and is not plug-and-play. It requires professional programming (adaptation) to your vehicle's specific keys, Engine Control Unit (ECU), and Electronic Steering Lock (ESL) to function.