Due to wear, high usage vehicles can experience ignition lock and tumbler failures. The ignition lock cylinder will generally require replacement to correct this concern.Google+
Car Problem Reports
Mercedes-Benz E420 High Usage Vehicles May Experience Ignition Lock and Tumbler Failures
Mercedes-Benz E420 Problem
Average Mileage: 149,377 mi (20,400 mi - 233,000 mi)
Visitor, 1997 Mercedes-Benz E420, 184,000 mi
Ignition switch was difficult to turn for a time, and eventually it stopped turning.
Visitor, 1997 Mercedes-Benz E420, 176,000 mi
The key just wouldn't turn. The dealership wants $1164 to fix it..... Can you say NUTS
Visitor, 1997 Mercedes-Benz E420, 233,000 mi
The ignition rey wont turn the tumbler
Visitor, 1997 Mercedes-Benz E420, 112,000 mi
I took it to the shop and it cost me $1300. I thought this was definitely overpriced.
For some time it was diffcult to turn the ignition using the key. Overtime it worsened, and finally I was unble to turn it at all.
Visitor, 1997 Mercedes-Benz E420, 180,000 mi
The switch will not turn at all. For some time, it was difficult, but eventually it would turn after a number of attempts. One day it stopped altogether.