Notes on installing brake pad wear sensor contact sensors - AH42.10-P-0003-01A
The following variants exist on the front axle: One contact sensor, two contact sensors or four contact sensors.
The following variants exist at the rear axle: No contact sensor, one contact sensor, two contact sensors or four contact sensors. Vehicles with ETS, ESP or ASR have contact sensors for the brake lining wear indicator.
| Model 171 | Version | Front axle | Rear axle |
| 171.442 | 5 | - | |
| 171.454 | 5 | - | |
| 171.456 | 5 | 10 |