Pressure test the low-voltage cooling/coolant loops on a 2024 Model Y Long Range AWD to identify leaks in the powertrain or battery coolant circuits. This is a diagnostic-only procedure — no coolant loop disassembly beyond cap removal.

Warnings

Tools required

Parts

• Replacement coolant reservoir cap (only if existing cap fails pressure hold) × 1 — OEM Tesla Model Y coolant reservoir cap

Fluids

• Tesla Battery/Motor Coolant (G-48) — top-up only if level drops during test — 0.5 qt

Preparation

1. Park on level ground, place in P, engage parking brake.
2. Exit ALL doors with key fob away from the vehicle. 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 in the front trunk area on 2024 Model Y — access via the front trunk floor/scuff trim and the LV service panel).
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. Allow the vehicle to sit and cool for at least 1 hour after any driving or charging before opening the cooling system. The Model Y cools the HV battery actively even at rest after fast-charging.
7. Open the frunk and locate the coolant reservoir (passenger-side area of the front compartment, behind the LV service panel cover).
8. Have shop towels staged around the reservoir to catch any residual coolant when removing the cap.

Procedure

1. 1

   Verify system is cool and depressurized
   Confirm the coolant reservoir is cool to the touch. Slowly rotate the reservoir cap to its first detent to vent any residual pressure, then pause. If you hear hissing, wait until it stops completely before fully removing the cap.
   ⚠️Removing the cap on a hot or pressurized system can spray coolant and cause severe burns.
2. 2

   Inspect coolant level and condition
   Note the current coolant level relative to the MIN/MAX indicators on the reservoir. Inspect coolant color and clarity — Tesla G-48 coolant should be a clear blue/green. Cloudy, oily, or discolored coolant indicates a contamination issue that pressure testing alone won't fully diagnose.
3. 3

   Visual leak inspection (pre-test baseline)
   Before pressurizing, visually inspect all accessible coolant hoses, clamps, and the reservoir for staining, weeping, or dried coolant residue. Use a flashlight and mirror to inspect the underside of the reservoir and the visible coolant lines in the frunk area. Do NOT inspect or probe lines under the vehicle near the HV battery — those are off-limits.
   ⚠Do not trace coolant lines into the HV battery enclosure or octovalve assembly. Limit inspection to the front compartment accessible coolant components.
4. 4

   Install pressure tester adapter
   Select the cap adapter from your pressure test kit that matches the Model Y reservoir neck. Thread the adapter onto the reservoir hand-tight — do not over-torque. Connect the pressure tester pump hose to the adapter.
5. 5

   Pressurize the system to specification
   Slowly pump the tester to pressurize the system to the rating stamped on the OEM coolant cap (do not exceed it). Pump in slow strokes and watch the gauge — stop immediately at the target pressure. If the cap is unmarked or unreadable, refer to the Tesla Service Manual for the specified test pressure rather than guessing.
   ⚠Over-pressurization can rupture plastic coolant fittings near HV components. Never exceed the cap's rated pressure.
6. 6

   Hold and observe for pressure decay
   Hold the system at test pressure for a minimum of 15 minutes. Monitor the gauge for any pressure drop. A stable reading indicates no significant external or internal leak in the accessible loop. A steady drop indicates a leak — proceed to leak localization.
7. 7

   Localize any leak (external)
   If pressure drops, re-inspect all visible hoses, clamps, the reservoir, the reservoir cap seat, and accessible coolant fittings for active weeping or bubbling. UV dye plus a UV light can help locate small leaks. Document the location with photos. If the leak originates from the octovalve, superbottle, HV battery coolant ports, or any drive unit coolant fitting: STOP and refer to Tesla service.
   ⚠️Leaks at the HV battery, octovalve, or drive unit housings are dealer-only repairs. Do not attempt to tighten, reseat, or replace these components.
8. 8

   Test the reservoir cap separately
   Remove the cap from the reservoir and install it on the cap-test fitting of the pressure tester (most kits include this). Pressurize the cap to its rated value. The cap must hold pressure and release at its rated relief pressure. Replace the cap if it fails to hold or relieves outside specification.
9. 9

   Release pressure and remove tester
   Slowly release pressure from the tester per the kit's instructions before removing the adapter. Once fully depressurized, unthread the adapter from the reservoir.
   ⚠Removing the adapter while pressurized will spray coolant. Always vent first.
10. 10

    Top up coolant if needed
    If the level dropped slightly during testing, top up with Tesla-spec G-48 battery/motor coolant only — do NOT substitute generic coolant. Bring the level to the MAX line. Do not overfill.
    ⚠Using non-Tesla-spec coolant can damage the HV battery thermal system and void warranty coverage.

Reassembly

1. Reinstall the coolant reservoir cap and tighten by hand to its detent/click — do not over-tighten.
2. Wipe down the reservoir and surrounding area to remove any spilled coolant; residual coolant can mimic a leak on future inspections.
3. Reinstall any frunk LV service panel covers or trim that were removed for access.
4. Reconnect the 12V low-voltage battery.
5. Close the frunk.

Verification

• Power on the vehicle and check the touchscreen for any thermal system, battery, or coolant-related alerts. No new alerts should appear.
• Allow the vehicle to idle in P for 10-15 minutes (or take a short drive) and re-check coolant level — it should remain stable at MAX.
• Re-inspect the reservoir, cap area, and accessible hoses for any new wetness after the drive cycle.
• If a leak was identified at a non-HV component and repaired, repeat the pressure test to confirm the repair holds.
• Note: Tesla now recommends battery coolant inspection at 4 years / 50,000 mi. Log this pressure test against that interval for future reference.

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