Pressure test the low-voltage coolant loop on a 2024 Model X to identify leaks in hoses, fittings, and the coolant reservoir. This is a diagnostic-only procedure — it does NOT involve the HV battery thermal loop, octovalve, or heat pump assembly.

Warnings

Tools required

Parts

• Replacement coolant reservoir cap (if cap fails pressure test) × 1 — OEM Tesla Model X coolant reservoir cap — match by part number on existing cap
• Coolant hose clamps (only if a leaking clamp is found) × 1 — Manufacturer-specified spring or worm clamp matching original

Fluids

• Tesla Battery/Motor Coolant (G-48) — top-up only if level drops — 1 qt

Preparation

1. Park on level ground, place in P, engage parking brake.
2. Exit ALL doors with the 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 frunk (similar position to Model S). Follow Tesla's documented frunk-access and 12V disconnect sequence.
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 coolant system to cool for at least 1 hour after any driving.
7. Disable Falcon door auto-presenting in the touchscreen (or keep fob well away) to prevent inadvertent door movement during the procedure.
8. Locate the LV coolant reservoir under the frunk liner / front service area. Identify it visually as the loop NOT connected to orange HV cabling. If identification is uncertain, STOP.

Procedure

1. 1

   Access the coolant reservoir
   Open the frunk and remove the frunk liner / service cover as required to expose the coolant reservoir. Note clip and fastener locations for reassembly.
   Torque spec

   Cover Screws11 Nm (8 lb-ft)
2. 2

   Visual pre-inspection
   Before pressurizing, inspect all visible coolant hoses, quick-connects, and the reservoir for staining, crusty residue, or wet spots. Note any findings — these are the prime suspects when pressure is applied.
3. 3

   Verify coolant level and condition
   Check that coolant is at the MIN/MAX line on the reservoir. Note the color — Tesla G-48 coolant is typically blue/green. Brown, rust-colored, or oily coolant indicates contamination and the test should be paused for further diagnosis.
4. 4

   Remove the reservoir cap
   Slowly rotate the reservoir cap counterclockwise to its first stop to release any residual pressure. Wait, then fully remove. Inspect the cap's seal and pressure relief mechanism for cracks or hardened rubber.
   ⚠Even a 'cool' EV coolant loop can hold residual pressure. Release slowly.
5. 5

   Test the cap separately
   Install the cap onto the pressure tester's cap-test adapter. Pump to the cap's rated pressure (stamped on the cap). The cap should hold pressure briefly and vent at its rated value. A cap that fails to hold or fails to vent must be replaced before proceeding.
6. 6

   Connect pressure tester to reservoir
   Select the adapter that matches the reservoir neck and thread it on hand-tight. Confirm the seal is fully seated. Connect the pressure tester pump to the adapter.
   ⚠A loose adapter will give a false leak reading and may eject under pressure.
7. 7

   Pressurize the system
   Slowly pump the tester up to the system's rated cap pressure (do NOT exceed it). Stop pumping immediately upon reaching the rating. Note the gauge reading.
   ⚠️Exceeding rated pressure can damage the heat pump assembly, plastic manifolds, or coolant jackets — repairs in this area can be five-figure jobs.
8. 8

   Hold and observe
   Allow the system to sit at pressure for a minimum of 15 minutes. The gauge should hold steady. A drop of more than ~1-2 psi indicates a leak.
9. 9

   Locate the leak
   If pressure drops, perform a careful visual and tactile inspection of all accessible hoses, the reservoir, hose-to-pump connections, and quick-connect fittings using an inspection mirror and flashlight. Look for fresh wet coolant. Do NOT inspect or probe near orange HV cabling, the HV battery, or the heat pump internals.
   ⚠️If the leak source appears to be the HV battery cooling jacket, octovalve/manifold, or heat pump assembly — STOP. This requires Tesla-certified HV-trained service.
10. 10

    Release pressure and disconnect tester
    Use the tester's bleed valve to slowly release system pressure to zero. Confirm the gauge reads 0 before unthreading the adapter from the reservoir.
11. 11

    Document findings
    Record the start pressure, end pressure, hold duration, cap test result, and any leaks identified. This is the deliverable from a pressure test — repairs are a separate job.

Reassembly

1. Reinstall the coolant reservoir cap, rotating clockwise until it clicks/seats fully.
2. Wipe down the reservoir and surrounding area to remove any spilled coolant — residue makes future leak diagnosis harder.
3. Reinstall the frunk liner / service cover. Torque any cover fasteners to OEM specification — refer to Tesla Service Manual.
4. Reconnect the 12V low-voltage battery in the frunk following Tesla's documented sequence.
5. Close the frunk and verify Falcon door operation is unaffected before returning the vehicle to service.

Verification

• Power the vehicle on and check the touchscreen for any thermal system, coolant level, or battery cooling alerts. No new alerts should be present.
• After a short test drive (5-10 minutes including some highway speed to allow the system to cycle), re-inspect the reservoir level and the area under the frunk for any fresh coolant residue.
• Recheck reservoir level after the system has cooled — it should remain between MIN and MAX.
• If this test was performed as part of the 4-year / 50,000 mi battery coolant inspection interval, log the date and mileage for the next inspection.
• If a leak was found and repaired, repeat the full pressure test to confirm the system holds pressure for 15 minutes.

More procedures for this vehicle