Replacement of the brake master cylinder on a 2024 Model Y Long Range AWD. This is a hydraulic-only job that does not require Tesla Toolbox for basic R&R, but a full brake bleed (and ideally a scan-tool-assisted iBooster/ABS bleed) is required afterward to restore proper pedal feel.

Warnings

Tools required

Parts

• Brake master cylinder assembly (OEM Tesla Model Y replacement) × 1 — Tesla Model Y master cylinder — verify exact part by VIN
• Master cylinder reservoir seal / grommets (if supplied separately) × 1 — OEM service kit per master cylinder
• Brake line sealing washers (if specified by service manual) × 1 — OEM specification

Fluids

• DOT 3 Brake Fluid (sealed, fresh container) — 1 qt

Preparation

1. Park on level ground, place in P, and engage the parking brake.
2. Exit ALL doors with the key fob away from the vehicle (minimum 10 m). Wait at least 2 minutes for HV systems to fully de-energize, even on this non-HV job.
3. Disconnect the 12V low-voltage battery (located behind/under the rear seat area on 2024 Model Y — refer to service manual for exact access). Insulate the negative terminal.
4. DO NOT touch, cut, or pierce ANY orange cable — these are high-voltage and lethal.
5. If at any point you encounter an orange cable, an HV component, or are unsure if a system is de-energized: STOP and consult a Tesla-certified technician.
6. Open the frunk and remove the frunk liner / tub as needed to access the brake master cylinder and booster assembly on the driver-side firewall area (LHD). Use trim tools — do not pry against painted surfaces.
7. Cover all painted surfaces and wiring near the master cylinder with plastic sheeting and absorbent rags.
8. Have a fresh, sealed bottle of DOT 3 brake fluid and a suitable catch container on hand before opening any hydraulic fitting.

Procedure

1. 1

   Evacuate brake fluid reservoir
   Using a clean, brake-fluid-dedicated syringe or transfer pump, remove as much fluid as possible from the master cylinder reservoir. Dispose of used fluid properly. Do NOT reuse old fluid.
   ⚠Never spill brake fluid on paint or wiring connectors — flush immediately with water if contact occurs.
2. 2

   Disconnect electrical connectors
   Identify and unplug the low-voltage connector(s) at the brake fluid level sensor on the reservoir and any connectors on the master cylinder / booster assembly. Note routing for reinstallation. Do not pull on wires — release the locking tabs at the connector body.
3. 3

   Disconnect hydraulic lines from master cylinder
   Using a proper flare-nut / line wrench, slowly loosen each brake line fitting at the master cylinder. Label each line by position (front/rear circuit) before fully removing. Cap each open line and port immediately with clean plugs to prevent contamination and excess fluid loss.
   ⚠Use a flare-nut wrench only — open-end wrenches will round the soft fittings and require line replacement.
   Torque spec

   Brake Line Fittings15 Nm (11 lb-ft)
4. 4

   Remove master cylinder mounting nuts
   Support the master cylinder by hand. Remove the nuts securing the master cylinder to the brake booster / firewall mounting studs. Do not let the unit hang on the lines or sensors.
   Torque spec

   Master Cylinder Nuts25 Nm (18 lb-ft)
5. 5

   Withdraw the master cylinder
   Pull the master cylinder straight off the booster studs. Be prepared to catch residual fluid. Inspect the booster pushrod seal area for fluid contamination — any sign of fluid past the seal indicates the booster also needs evaluation by a Tesla-certified technician.
   ⚠️If fluid is found inside the booster bore or on the booster diaphragm, STOP. The integrated electronic booster is not a DIY-serviceable component.
6. 6

   Bench-prep the new master cylinder
   Transfer the reservoir to the new master cylinder if supplied separately, using new grommets per the OEM service kit. Bench bleed the new master cylinder per the unit manufacturer's instructions using clean DOT 3 fluid until no air bubbles return through the bleed tubes.
   ℹ️Skipping the bench bleed will trap air at the highest point of the system and produce a permanently spongy pedal.
7. 7

   Install new master cylinder
   Align the new master cylinder onto the booster studs, ensuring the pushrod is correctly seated in the master cylinder bore. Install the mounting nuts hand-tight, then torque evenly in a cross pattern to the manufacturer-specified value. Verify sequence with the Tesla Service Manual.
   ⚠Uneven torque can cock the master cylinder on the studs and cause internal seal damage or fluid leaks.
   Torque spec

   Master Cylinder Nuts25 Nm (18 lb-ft)
8. 8

   Reconnect brake lines
   Start each brake line fitting by hand to avoid cross-threading. Once all lines are started, tighten with a flare-nut wrench to the verified line fitting torque. Confirm orientation against the labels you applied during removal.
   Torque spec

   Brake Line Fittings15 Nm (11 lb-ft)
9. 9

   Reconnect electrical connectors
   Reattach the brake fluid level sensor and any other connectors removed earlier. Confirm each connector clicks fully into its lock.
10. 10

    Fill reservoir and bleed the brake system
    Fill the reservoir to the MAX line with fresh DOT 3 brake fluid. Bleed each caliper in the manufacturer-specified sequence using a pressure or two-person bleed method until clean, air-free fluid emerges from each bleeder. Top up the reservoir continuously — do not let it run dry. Torque each bleeder screw to spec when finished. Install the reservoir cap hand-tight.
    ⚠A manual bleed alone will NOT purge air from the integrated electronic booster/ABS module. A scan-tool-initiated ABS bleed is required for full pedal restoration.
11. 11

    Perform ABS / electronic booster bleed
    Reconnect the 12V battery. Using a Tesla-compatible diagnostic scan tool, command an ABS / electronic booster bleed cycle. Repeat the wheel-circuit bleed afterward to capture any air dislodged from the module. If you do not have access to a capable scan tool, the vehicle should be brought to a Tesla-certified facility before being driven.
    ⚠️Do NOT road test the vehicle until the ABS bleed has been completed and the pedal is firm. A spongy pedal in a Tesla also disables proper regen-to-friction blending under hard braking.

Reassembly

1. Verify all brake line fittings are torqued and dry — wipe each connection with a clean rag and re-inspect after a few pedal cycles.
2. Top off the reservoir to the MAX line with fresh DOT 3 fluid; install the cap hand-tight.
3. Reinstall the frunk tub / liner and any trim removed for access.
4. Reconnect the 12V battery negative terminal if not already done for the ABS bleed.
5. Clear any DTCs set during service using the diagnostic tool.
6. Wake the vehicle and confirm no brake-related warnings on the center display (no 'Service Brake System', no 'ABS', no 'Traction Control' faults).

Verification

• With the vehicle off, pump the brake pedal — it should become firm within 2–3 strokes and not sink under sustained foot pressure.
• Power the vehicle on; the pedal should rise/firm up as the electronic booster pressurizes, with no audible air or hydraulic gurgle.
• Check the center display for any brake, ABS, traction control, or stability control warnings. All must be clear before driving.
• Inspect every fitting and the master cylinder base for weeping fluid after 5 brake pedal applications and again after a short low-speed test.
• Perform a low-speed (under 10 mph), straight-line brake test in a safe area to confirm even, non-pulling stops before normal driving.
• Confirm regenerative braking and one-pedal driving behave normally — abnormal regen drop-off can indicate residual air in the booster/ABS module.
• Note: Tesla recommends brake fluid replacement every 2 years — record this service date so the next interval is scheduled correctly.

More procedures for this vehicle