Brake Booster Check Valve

Inspection and replacement of the brake booster check valve on the 2025 Rivian EDV 500's electro-hydraulic brake system to ensure proper vacuum assist and brake pedal feel.

Warnings

Tools required

Parts

• Brake booster check valve × 1 — Use OEM specification
• Check valve grommet × 1 — Use OEM specification
• Vacuum hose (if damaged) × 1 — Use OEM specification

Fluids

• DOT 4 Brake Fluid — 0.25 qt

Preparation

1. Park vehicle on level ground and engage parking brake
2. Turn off vehicle and remove key fob from cabin
3. Open hood and secure with prop rod
4. Disconnect 12V negative battery terminal and wait 5 minutes for system capacitors to discharge
5. Place towels or absorbent pads around brake booster area to catch any brake fluid drips
6. Photograph vacuum hose routing and check valve orientation for reference during reassembly
7. If available, connect diagnostic tool to check for pre-existing brake system fault codes

Procedure

1. 1

   Locate brake booster and check valve
   The brake booster is mounted on the firewall on the driver's side. Trace the vacuum line from the electric vacuum pump (mounted near the front motor assembly) to the brake booster. The check valve is typically installed inline in this vacuum hose or directly into the brake booster housing. On the EDV 500, the check valve is integrated into the booster inlet port.
2. 2

   Remove engine cover if necessary
   If the electric motor cover obstructs access to the vacuum pump or check valve, remove fasteners securing the cover. Use a 10mm socket to remove cover bolts. Carefully lift the cover away and set aside in a clean area.
3. 3

   Inspect vacuum hose condition
   Examine the entire length of vacuum hose from pump to booster for cracks, hardening, or deterioration. Check for oil contamination which indicates vacuum pump failure. If hose shows any damage, plan to replace it along with the check valve.
4. 4

   Test existing check valve function
   Before removal, verify the check valve is faulty. Disconnect the vacuum hose from the booster side of the check valve. Attempt to blow air through the valve toward the booster - air should not pass. Then attempt to draw air (suction) from the booster side - air should flow freely. If the valve fails either test, replacement is required.
5. 5

   Release vacuum hose clamp
   Locate the hose clamp securing the vacuum line to the check valve. Use needle-nose pliers to compress spring-type clamps or a flathead screwdriver to loosen worm-drive clamps. Slide the clamp away from the check valve connection point along the hose.
6. 6

   Disconnect vacuum hose from check valve
   Grasp the vacuum hose firmly near the check valve connection. Twist gently while pulling to separate the hose from the valve. If the hose is stuck due to age, carefully work a small flathead screwdriver between the hose and valve fitting to break the seal. Avoid tearing the hose unless replacement is already planned.
7. 7

   Remove check valve from brake booster
   The check valve typically inserts into a grommet in the brake booster housing. Grasp the check valve body firmly and pull straight out with steady pressure. The valve should release from the grommet. If the grommet comes out with the valve, this is normal - inspect the grommet for damage and replace if cracked or deteriorated.
8. 8

   Inspect booster port and grommet seat
   Examine the brake booster inlet port where the check valve was installed. Look for cracks, debris, or damage to the port. If the grommet remained in the booster, use needle-nose pliers to extract it. Clean the port opening with a lint-free cloth. Do not allow any debris to enter the booster housing.
9. 9

   Install new grommet
   Take the new check valve grommet and lubricate the outer surface lightly with clean DOT 4 brake fluid. Press the grommet into the brake booster inlet port by hand, ensuring it seats fully and evenly in the mounting hole. The grommet should be flush with or slightly below the booster housing surface.
10. 10

    Install new check valve
    Verify the new check valve orientation - the arrow on the valve body must point toward the brake booster (direction of vacuum flow). Insert the check valve into the newly installed grommet with firm, steady pressure until it seats completely. The valve should click or bottom out in the grommet.
11. 11

    Reconnect vacuum hose
    Push the vacuum hose onto the check valve fitting until it seats against the valve body. Ensure the hose is fully inserted - you should feel it bottom out. Slide the hose clamp into position over the connection point, positioning it approximately 1/4 inch from the end of the hose. Tighten or secure the clamp properly.
12. 12

    Verify all connections
    Trace the entire vacuum line from pump to check valve to booster, ensuring all connections are secure and properly clamped. Verify the check valve arrow points toward the booster. Ensure no vacuum hoses are kinked, pinched, or routed near sharp edges or hot surfaces.
13. 13

    Reinstall engine cover
    If removed, reinstall the motor cover by aligning mounting points and installing fasteners finger-tight first, then torque in a cross-pattern. Since no torque specification is provided, tighten securely but do not over-torque plastic mounting points.
14. 14

    Reconnect battery and clear codes
    Reconnect the 12V negative battery terminal. If using a diagnostic tool, clear any brake system fault codes that may have been triggered. The vehicle may need to relearn idle and brake system parameters.

Reassembly

1. Ensure all vacuum connections are secure and properly clamped
2. Verify no tools or materials are left in the engine compartment
3. Reinstall any covers or shields removed for access
4. Double-check that the check valve arrow points toward the brake booster

Verification

• Start the vehicle and listen for the electric vacuum pump to activate briefly, then shut off as vacuum builds
• With the engine running, press the brake pedal - it should feel firm with normal assist. A hard pedal indicates vacuum system failure
• Turn off the vehicle and wait 1 minute. Press the brake pedal - you should get 2-3 power-assisted applications before the pedal becomes hard, confirming the check valve is holding vacuum
• Test drive the vehicle in a safe area at low speed to verify normal brake operation and pedal feel
• Use diagnostic tool to verify no brake system fault codes are present
• Check for vacuum leaks by listening for hissing sounds around all vacuum connections with the pump running
• Re-inspect all connections after test drive for any signs of leakage or looseness

Related trouble codes on this vehicle

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