2021 Mercedes-Benz AMG GT Front Brake System Update

Mercedes-Benz has released field measure 21P4396101 to ensure that the front axle brake system of certain 2021 Mercedes-Benz AMG GT vehicles, identified as Model 190 with M032 (BLACK SERIES VERSION), is brought up to current series production specifications. This proactive update involves the removal and replacement of various components related to the front brake system and surrounding areas.

This field measure, identified by code 21P4396101, is a technical service bulletin (TSB) that outlines a detailed work procedure for technicians. Owners of affected vehicles should be aware of the scope of this update and the components involved.

Important Warnings for Technicians and Owners

Several critical instructions are provided within the field measure to ensure proper execution and safety:

• When replacing components, it is explicitly stated that "All screws must be replaced!" in multiple steps, including the removal of the lower engine compartment lining, front bumper, radiator protection grille, and air ducting.
• The original left and right front fender liners are "no longer needed (will be replaced)!" as part of this update.
• Similarly, the original air ducting is "no longer needed (will be replaced)!"
• During the removal of the brake caliper, technicians are warned: "Do not open hydraulically!" This prevents potential issues with the brake system.
• When wrapping heat protection around the rotational speed sensors, the instruction is to "Do not wrap heat protection around too tightly – leave a small air gap for optimized insulation."

Repair Procedure Summary

The work procedure for field measure 21P4396101 is comprehensive, involving multiple stages to update the 2021 Mercedes-Benz AMG GT front brake system. The process begins with the careful disassembly of various front-end components.

Initial Disassembly

Technicians first remove both front wheel and tire assemblies. This is followed by the removal of the lower engine compartment lining, front and rear fender liners, the front bumper, and the radiator protection grille. The air ducting (A, Figure 1) is also removed. Throughout these steps, specific instructions emphasize that all screws and expansion rivets must be replaced with new ones.

Low-Temperature Water System Modifications

The left low-temperature water hose (C, Figure 3) is extended using adapter A 190 501 67 00 (Figure 5). This involves clamping off the water hose (D, Figure 4) and paying close attention to the position of the color marking (white line) (E, Figure 6). Subsequently, the low-temperature circuit is checked for leaks. New air hoses A 190 428 31 00 (F, Figures 7 and 8) are installed on both sides, with specific guidance on rotation and ensuring the color marking is flush with the body-in-white (G, Figure 9).

Horn and Holder Adjustments

Holders for the horns on both sides are removed. The right holder (H, Figure 10) is no longer required. The right horn is then attached to a new holder, part number A 190 501 66 00 (I, Figure 10). An edge guard is mounted on this new right holder (J, Figure 11). Finally, new right and left holders with horns are installed on new air ducting, part number A 190 505 36 00 (K, Figure 12), using expansion rivets from the outside to the inside (L, Figure 13).

Brake System Component Removal

The brake caliper is removed and secured with a special tool, with a strict warning not to open it hydraulically. The brake disk is then removed. Top left and right heat shields (P, Figure 17) are also removed, followed by the removal of the left and right front axle rotational speed sensors from the steering knuckle. All screws associated with these components must be replaced.

Heat Protection Application

Heat protection, part number A 004 997 08 51, is wrapped around the removed left and right front axle rotational speed sensors. This protection is cut to a length of 150 mm each (Figure 18) and attached with three cable ties, part number A 000 995 97 06, per sensor. Care must be taken not to wrap the heat protection too tightly, leaving a small air gap for optimal insulation (Figure 19).

Brake System Component Installation

New brake cover plates (A 190 421 47 01 / A 190 421 48 01) (Q, Figure 20) and screening plates (A 190 421 67 01 / A 190 421 68 01) (R, Figure 21) are installed on both sides. Front guide vanes (A 190 421 43 01 / A 190 421 44 01) and rear guide vanes (A 190 421 51 01 / A 190 421 52 01 / A 190 421 45 01 / A 190 421 46 01) are replaced.

Reassembly and Fluid Management

The front bumper is reinstalled, followed by the installation of new front fender liners (A 190 690 01 02 / A 190 690 02 02) and the old ones at the rear in the front fender, paying attention to the cutout for air hoses (S, Figure 22). New connection fittings (A190 885 65 04 / A 190 885 66 04) are installed at the left and right of the wheel well liner (T, Figure 23). The lower engine compartment lining is reinstalled. Finally, the low-temperature circuit coolant is filled and bled using a diagnostic system, with a mixing ratio of 40:60. All remaining components are assembled in reverse order.

Required Parts

This field measure requires numerous specific parts to complete the 2021 Mercedes-Benz AMG GT front brake update. Below is a detailed list of components and their part numbers:

Quantity	Designation	Part no.
21	Fillister head screw M6x20	A 010 990 26 04
6	Bolt and washer assembly M6x55	N 304017 006028
4	Screw	A 010 990 17 04
4	Fillister head screw	N 000000 001476
4	Sheet metal screw 4.8x19	N 000000 000925
8	Hexagon head bolt M6	N 910143 006002
4	Expansion rivet	A 201 990 02 92 9051
2	Plastic nut	A 000 990 28 62
1	Left bracing	A 190 620 45 02
1	Right bracing	A 190 620 46 02
2	Expansion rivet	A 000 991 41 40
1	Air ducting	A 190 505 36 00
1	Right holder	A 190 501 66 00
2	Nut	N 910112 006002
1	Hose line	A 190 501 67 00
1	Left front wheel well liner	A 190 690 01 02
1	Right front wheel well liner	A 190 690 02 02
6	Bolt and washer assembly	A 163 990 01 36
6	Plastic nut	A 000 990 35 62
6	Expansion rivet	A 000 990 54 92 9051
12	Spring lock nut	A 004 994 17 45
2	Flexible hose	A 190 428 31 00
1	Left connection fitting	A 190 885 65 04
1	Right connection fitting	A 190 885 66 04
6	Expansion rivet	A 000 990 90 92
2	Sheet metal screw	N 000000 000815
2	Spring lock nut	A 003 994 85 45
4	Cap bolt	A 003 990 79 05
2	Safety screw	A 220 421 01 71
2	Screw, M6x20	N 000000 005050
6	Safety screw	A 000 421 13 71
1	Left cover panel	A 190 421 47 01
1	Right cover panel	A 190 421 48 01
1	Left screening plate	A 190 421 67 01
1	Right screening plate	A 190 421 68 01
4	Screw, M6x12	N 000000 007932
1	Heat protection (2x 150 mm)	A 004 997 08 51
6	Cable tie	A 000 995 97 06
1	Left air scoop	A 190 421 43 01
1	Right air scoop	A 190 421 44 01
6	Hexalobular bolt M6	N 000000 006341
1	Left upper transverse control arm air scoop	A 190 421 51 01
1	Right upper transverse control arm air scoop	A 190 421 52 01
2	Cable tie	A 203 997 04 90
1	Left lower transverse control arm air scoop	A 190 421 45 01
1	Right lower transverse control arm air scoop	A 190 421 46 01
8	Sheet metal screw 4.8x16	N 000000 000548
8	Clip-on nut	A 003 994 87 45

Owner Action

If you own a 2021 Mercedes-Benz AMG GT, specifically Model 190 with M032 (BLACK SERIES VERSION), it is recommended to contact your authorized Mercedes-Benz dealer to inquire about field measure 21P4396101. This update ensures your vehicle's front brake system components are configured to the latest production standards. The dealer will be able to confirm if your vehicle is affected and schedule the necessary service.

Source: NHTSA ID 10208673