Battery cooling system service on the 2012 Tesla Roadster involves draining, flushing, and refilling the battery (ESS) coolant loop. Note that the Roadster's cooling system is integrated with the high-voltage Energy Storage System, and significant portions of this work require HV-trained personnel.

Warnings

Tools required

Parts

• Coolant hose clamps (as required if reused clamps are worn) × 1 — OEM-specified spring or worm-gear clamps
• Coolant reservoir cap (inspect; replace if seal degraded) × 1 — OEM-specified Roadster ESS reservoir cap

Fluids

• Tesla Battery/Motor Coolant (G-48 specification) — 10 qt

Preparation

1. TESLA SAFETY PREAMBLE: Park on level ground, place transmission in neutral or park-equivalent, engage the parking brake, and chock the wheels.
2. TESLA SAFETY PREAMBLE: Exit all doors with the key fob carried well away from the vehicle. Wait at least 2 minutes for HV systems to fully de-energize, even though this job is not directly HV.
3. TESLA SAFETY PREAMBLE: Disconnect the 12V low-voltage auxiliary battery (located in the front trunk/frunk compartment area on the 2012 Roadster). Insulate the negative terminal so it cannot contact the post.
4. TESLA SAFETY PREAMBLE: DO NOT touch, cut, or pierce ANY orange cable — these are high-voltage and lethal.
5. TESLA SAFETY PREAMBLE: 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 coolant is at ambient temperature. The Roadster's PEM and ESS coolant loops can retain heat and pressure.
7. Raise and support the vehicle on a lift or jack stands at the manufacturer-specified jacking points (the Roadster uses Lotus-style chassis jacking pads — do not jack on the floor pans).
8. Remove the rear access panels / undertray as required to access the coolant reservoir, pump, and accessible coolant lines. Retain all fasteners by location.

Procedure

1. 1

   Identify scope of service
   Confirm that the work to be performed is limited to the externally accessible portion of the battery cooling loop: the coolant reservoir, external hoses between the reservoir and the ESS inlet/outlet bulkhead fittings, the coolant pump, and the radiator/heat exchanger. Any work that requires opening the ESS enclosure or disconnecting lines inside the pack is HV-restricted and must not proceed under this guide.
   ⚠️If the planned service requires opening the ESS or disconnecting HV-side cooling internals, stop now and refer to a Tesla-certified Roadster specialist.
2. 2

   Inspect the cooling system
   Visually inspect all accessible coolant hoses, clamps, the reservoir, the coolant pump, and the heat exchanger for leaks, weeping, swelling, chafing, or corrosion. Note any components that need replacement before proceeding to drain.
3. 3

   Relieve system pressure
   With the system fully cooled, slowly loosen the coolant reservoir cap to release any residual pressure, then remove the cap and set it aside on a clean surface. Inspect the cap seal; replace if cracked or hardened.
   ⚠Even with the system cool, residual pressure can remain. Loosen the cap slowly with a rag over it.
4. 4

   Drain the battery coolant loop
   Position a clean drain pan rated for at least 12 quarts beneath the lowest accessible point of the cooling loop. Open the manufacturer-specified drain point (typically a low hose connection on the externally routed coolant line near the heat exchanger). Allow the system to drain completely. Capture the old coolant for proper disposal — G-48 coolant is toxic and must not be poured down a drain.
   ⚠Used coolant from the battery loop may contain trace contaminants. Handle with gloves and dispose at an approved facility.
   Torque spec

   Coolant Line Fittings15 Nm (11 lb-ft)
5. 5

   Inspect and replace external hoses if required
   With the system drained, inspect each accessible external coolant hose for internal degradation, soft spots, or clamp imprint damage. Replace any hose that is suspect using OEM-specified replacement hoses and clamps. Do not disconnect any hose that enters the ESS enclosure or is bonded to an HV-adjacent component.
   Torque spec

   Coolant Line Fittings15 Nm (11 lb-ft)
6. 6

   Inspect the coolant pump and heat exchanger
   Check the externally mounted coolant pump for leaks at the shaft seal and electrical connector for corrosion. Inspect the heat exchanger fins for debris and straighten as needed. If the pump or heat exchanger is being replaced, follow the manufacturer-specified procedure and torque mounting hardware to OEM specification.
   Torque spec

   Mounting Bolts27 Nm (20 lb-ft)

   Bracket Bolts20 Nm (15 lb-ft)
7. 7

   Reconnect drain point and prepare for fill
   Reinstall the drain plug or reconnect the drain hose using a new clamp if the original is fatigued. Verify all hose clamps along the externally accessible loop are properly seated and tightened. Confirm the reservoir cap is off and ready for fill.
   Torque spec

   Coolant Line Fittings15 Nm (11 lb-ft)
8. 8

   Fill with Tesla-specified G-48 coolant
   Using a vacuum-fill tool (preferred) or slow gravity fill, add Tesla Battery/Motor Coolant (G-48 specification). Approximate system capacity is 10.0 qt — actual quantity will vary based on residual fluid. Fill to the MAX mark on the reservoir. Do not substitute non-G-48 coolant.
   ⚠Vacuum filling is strongly recommended on the Roadster cooling loop to avoid trapped air pockets near the ESS heat exchanger.
9. 9

   Bleed the system
   Follow the manufacturer-specified bleed procedure for the Roadster ESS coolant loop. With the reservoir cap off, allow trapped air to migrate to the reservoir. Top off as the level drops. The Roadster typically requires the coolant pump to be cycled to circulate fluid through the ESS — this normally requires Tesla diagnostic software. If you do not have access to that software, STOP and consult a Tesla-certified technician to complete the bleed.
   ⚠An incompletely bled battery cooling loop can cause localized hot spots in the ESS. Do not return the vehicle to service until bleeding is verified complete.
10. 10

    Final top-off and cap installation
    After bleeding, verify coolant level is at the MAX mark with the system cold. Install the reservoir cap and confirm it seats and locks per OEM design.
11. 11

    Reconnect 12V battery
    Remove terminal insulator and reconnect the 12V auxiliary battery negative terminal. Torque to OEM specification — refer to Tesla Service Manual.

Reassembly

1. Reinstall any rear access panels and undertray panels removed for access, using original fasteners in original locations.
2. Lower the vehicle to the ground from the manufacturer-specified jacking points.
3. Wipe down the engine bay / rear bay area to remove any spilled coolant — residue makes future leak detection harder.
4. Dispose of used coolant at an approved hazardous waste facility.

Verification

• With the vehicle powered on, verify no warning messages related to ESS cooling, pump fault, or coolant level appear on the VDS (Vehicle Display Screen).
• After a short drive cycle, allow the vehicle to cool fully and recheck the reservoir level — top off if it has dropped, indicating remaining trapped air.
• Inspect every disturbed hose connection and the reservoir cap for leaks or weeping after the first heat cycle.
• Confirm the coolant pump runs (audible from the rear of the vehicle) when the ESS calls for cooling.
• Tesla's historical guidance treated battery coolant as 'lifetime,' but current Tesla guidance recommends inspection every 4 years / 50,000 miles. Log this service date and mileage so the next inspection interval is known.
• If any doubt remains about bleed completeness or system function, have the vehicle evaluated by a Tesla-certified Roadster technician before extended driving.

More procedures for this vehicle