Pressure test the cooling system on a 2024 Tesla Cybertruck Dual Motor to identify external leaks or internal seal failures in the low-temperature coolant loop. This is a non-invasive diagnostic that does NOT require opening the HV battery thermal loop — only the accessible coolant reservoir is pressurized.

Warnings

Tools required

Parts

• Coolant reservoir cap (replace if seal is suspect) × 1 — OEM Cybertruck coolant reservoir cap

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 48V low-voltage battery per Tesla's documented procedure for Cybertruck (48V architecture — NOT 12V). Locate the LV battery under the front trunk floor / frunk area as documented in the service manual.
4. DO NOT touch, cut, or pierce ANY orange cable — these are high-voltage and lethal at 800V on this vehicle.
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 until the cooling system is fully at ambient temperature (no recent driving, charging, or preconditioning).
7. Open the frunk to access the coolant reservoir area. Place fender covers on adjacent stainless panels.
8. Identify the correct reservoir: this test applies ONLY to the accessible powertrain/accessory coolant reservoir. Do not attempt to test the sealed HV battery thermal circuit.

Procedure

1. 1

   Visual pre-inspection
   With the system cold, inspect the coolant reservoir, visible hoses, hose clamps, and the underside of the front compartment for staining, crusty residue (G-48 dries to a chalky film), or active drips. Note any suspect areas before pressurizing — pressure testing will amplify a small weep into a clear leak.
2. 2

   Verify coolant level
   Confirm coolant level is between MIN and MAX on the reservoir. If low, top up with Tesla Battery/Motor Coolant (G-48 spec) before testing — do not substitute generic green or OAT coolants. If the system is significantly low, find and address the cause before pressurizing.
   ⚠Do not use non-G-48 coolant. Mixing chemistries can damage seals and aluminum components in the thermal loop.
3. 3

   Remove the reservoir cap
   Slowly rotate the reservoir cap counter-clockwise to its first detent to release any residual pressure, then fully remove it. Inspect the cap's rubber seal for cracks, swelling, or deformation — a failed cap seal is a common cause of pressure loss and false-positive leak symptoms.
   ⚠️If you hear pressure release or see steam, the system is NOT cold. Stop and let it cool fully.
4. 4

   Install the pressure tester adapter
   Select the adapter from your pressure tester kit that matches the Cybertruck reservoir neck (typically a European/Tesla-style threaded or bayonet adapter — verify fitment without forcing). Thread or lock the adapter onto the reservoir per the tester manufacturer's instructions, then connect the pump assembly.
   ⚠Do not force a mismatched adapter — cross-threading the reservoir neck will require reservoir replacement.
5. 5

   Pressurize the system
   Slowly pump the tester up to the system's rated cap pressure as marked on the OEM reservoir cap (do NOT exceed it). If the cap pressure is not legible, pressurize conservatively to a typical low-pressure cooling system value and stop — over-pressurization can rupture seals or hoses. Watch the gauge as you pump.
   ⚠Never exceed the cap's rated pressure. The Cybertruck's powertrain cooling loop is a low-pressure system; over-pressurizing can damage plastic reservoirs, quick-connects, and seals.
6. 6

   Hold and observe pressure
   Allow the system to hold pressure for a minimum of 10–15 minutes. A stable gauge indicates no significant external or internal leak in the tested loop. A slow drop indicates a leak — proceed to step 7. A rapid drop indicates a major leak — depressurize immediately and locate the source visually.
7. 7

   Locate the leak
   With the system held under pressure, inspect with a flashlight and mirror/borescope: reservoir body and seams, all accessible hose-to-fitting joints, quick-connect couplers, the radiator end tanks where visible, and the underside of the front compartment. Look for fresh wet coolant or drip points. Mark suspect areas. Do NOT trace leaks into the HV battery enclosure or near orange HV cabling — if the leak appears to originate from a sealed thermal manifold, octovalve, or the battery loop, STOP.
   ⚠️If coolant is observed leaking from the HV battery thermal loop, octovalve/manifold area, or near orange HV cabling, this is outside the scope of this procedure. Depressurize and refer to a Tesla-certified technician.
8. 8

   Test the cap (optional but recommended)
   Many pressure tester kits include a cap adapter. Install the reservoir cap on the cap adapter and pressurize to the cap's rated value. The cap should hold pressure and then release at its rated pop-off value. If it leaks below rating or fails to release, replace the cap.
9. 9

   Depressurize and remove tester
   Use the tester's bleed valve to slowly release all pressure before disconnecting. Never crack the adapter loose under pressure. Once at zero, remove the adapter from the reservoir.

Reassembly

1. Wipe the reservoir neck and cap seal clean with a lint-free towel.
2. Verify coolant level is at the correct cold-fill mark; top up with G-48 spec coolant if needed.
3. Reinstall the reservoir cap (or a new cap if the old one failed testing) and tighten to the cap's hand-tight detent — do not over-tighten.
4. Remove fender covers and any shop materials from the frunk area.
5. Reconnect the 48V low-voltage battery in the reverse order it was disconnected.
6. Close the frunk.

Verification

• Power the vehicle on and check the touchscreen for any cooling system, thermal, or battery temperature alerts.
• Allow the vehicle to run a thermal cycle (a short drive or a Supercharging session triggers active thermal management). Re-inspect the reservoir and previously suspect areas for new wetness once cooled.
• Recheck coolant level after the thermal cycle — a small drop on first cycle is normal as air purges; a continued drop indicates an unresolved leak.
• Confirm no new alerts appear over the next 24–48 hours of normal use.
• Tesla recommends battery coolant inspection at 4 years / 50,000 mi — log this pressure test against that interval so the next inspection can be scheduled accordingly.

More procedures for this vehicle