Replacement: brake pad wear sensor – Mercedes W204. AUTODOC recommends:
The replacement procedure is identical for both brake pad wear sensors on the same axle.
The wear sensors should be replaced together with the brake pads.
Please note: all work on the car – Mercedes W204 – should be done with the engine switched off.
Carry out replacement in the following order:
Step 1
Open the bonnet. Unscrew the brake fluid reservoir cap.
Step 2
Secure the wheels with chocks.
Step 3
Loosen the wheel mounting bolts. Use wheel impact socket #17.
Step 4
Raise the car.
Replacement: brake pad wear sensor – Mercedes W204. Tip from AUTODOC:
If you are using a jack, make sure it rests on a flat surface without any unevenness.Be sure to additionally secure the car with jack stands.
Step 5
Unscrew the wheel bolts.
AUTODOC recommends:
Warning! To avoid injury, hold the wheel while unscrewing the fastening bolts. Mercedes W204
Step 6
Remove the wheel.
Step 7
Detach the connector of the brake pad wear sensor. Use long nose pliers.
Step 8
Clean the fasteners of the brake pad wear sensor wiring harness. Use a wire brush. Use WD-40 spray.
Step 9
Unscrew the fasteners of the brake pad wear sensor wiring harness. Use Torx E10. Use a ratchet wrench.
Step 10
Remove the fastening bolt.
Step 11
Detach the brake pad wear sensor wiring harness.
Step 12
Detach the brake caliper retaining spring. Use a crowbar.
Step 13
Remove the dust boot caps of the brake caliper guide pins. Use a crowbar.
Step 14
Unscrew the brake caliper fasteners. Use HEX No.H7. Use a ratchet wrench.
Step 15
Spread the brake pads. Use a crowbar.
Step 16
Remove the brake caliper.
Replacement: brake pad wear sensor – Mercedes W204. Tip:
Tie the caliper to the suspension or to the body with a wire without disconnecting from the brake hose to prevent depressurization of the brake system.Make sure that the brake caliper is not hanging on the brake hose.Don't press the brake pedal after the brake caliper has been removed. As a result, the piston can fall out from the brake cylinder, and brake fluid leakage and depressurization of the system may occur.
Step 17
Remove the brake pads.
Step 18
Clean the brake caliper bracket from dirt and dust. Use a wire brush. Use a brake cleaner.
AUTODOC recommends:
After applying the spray, wait a few minutes.Check the brake caliper bracket, brake caliper guide pins and boots. Clean them. Replace, if necessary.
Step 19
Treat the brake caliper piston. Use a nylon cleaning brush. Use a brake cleaner.
AUTODOC recommends:
Replacement: brake pad wear sensor – Mercedes W204. After applying the spray, wait a few minutes.Check the brake caliper bracket, brake caliper guide pins and boots. Clean them. Replace, if necessary.
Step 20
Press in the brake caliper piston. Use brake caliper wind back tool.
Step 21
Attach the new wear sensor to the new pad.
Step 22
Treat the brake pads in the area where their surface comes into contact with the brake caliper bracket. Use anti-squeal paste.
AUTODOC recommends:
Make sure the disc surface is clean before installing the pads.
Step 23
Install the brake pads.
Step 24
Install the brake caliper and fix it.
Step 25
Tighten the brake caliper fasteners. Use HEX No.H7. Use a torque wrench. Tighten it to 25 Nm torque.
Step 26
Install the dust boot caps of the brake caliper guide pins.
Step 27
Attach the brake pad wear sensor wiring harness.
Step 28
Install the fastening bolt.
Step 29
Tighten the fasteners of the brake pad wear sensor wiring harness. Use Torx E10. Use a torque wrench. Tighten it to 8 Nm torque.
Step 30
Treat the brake pad wear sensor plug. Use dielectric grease.
Step 31
Attach the connector of the brake pad wear sensor.
Step 32
Install the brake caliper retaining spring.
Step 33
Clean the wheel rim mounting seat. Use a wire brush.
Step 34
Treat the surface where the brake disc contacts the wheel rim. Use ceramic grease.
Step 35
Clean the brake disk surface. Use a brake cleaner.
AUTODOC recommends:
After applying the spray, wait a few minutes.
Step 36
Install the wheel.
AUTODOC recommends:
Important! Hold the wheel while screwing in the fastening bolts. Mercedes W204
Step 37
Screw in the wheel bolts. Use wheel impact socket #17.
Step 38
Lower the car and working in a cross order, tighten the wheel bolts. Use wheel impact socket #17. Use a torque wrench. Tighten it to 130 Nm torque.
Step 39
Remove the jacks and chocks.
AUTODOC recommends:
Without starting the engine, press the brake pedal several times until you feel significant resistance.Check the brake fluid level in the expansion tank and refill if necessary.
Step 40
Tighten the brake fluid reservoir cap. Close the hood.
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