2017 Mercedes Benz C 43 AMG Diagnostic and Repair# P-80_57-20 Date: 030225

Audio System - RF Interference Explanation
Date: February 25, 2003
Order No.: P-B-80.57/20
Supersedes:
Group: 80.57
SUBJECT:
Models 129, 140, 170, 202, 203, 208, 209, 210, 211, 215, 220 and 230
Mercedes Benz C 43 AMG (202.033) V8-4.3L (113.944) Page 155
Radio Interference for RF Keys
A number of different RF operated Systems are active such as cordless headphones, garage door openers, remote reading thermometers, etc. when
active, operate within the frequency range of the remote control key as well as the keyless go cards and keys. These transmitters operate with several
times the power output of the key or card whose frequency and power output is limited by size.
If one of the above mentioned RF operated Systems is located near the vehicle and is active, strong interference could be present which occasionally
could prevent the vehicle from being locked/unlocked or starting the engine.
In such circumstances, model 170 vehicles which are only equipped with an RF remote key can be locked/unlocked using the mechanical key. All
other vehicles have an IR system in parallel to the RF system so the vehicle can be locked/unlocked from a short distance at any time.
This is not an indication of a defect, merely the limitations of operation in the presence of other stronger radio frequency emitters. If the customer
experiences this circumstance, please explain the cause.
Please also observe the corresponding notes in the 215, 220 and 230 Owner's Manual for keyless go cards recommending that the driver carry the
vehicle key as well, as that would help avoid any difficulties arising from this circumstance.