Volkswagen ID.4: Checking and filling engine coolant

• Preparations
• Checking the coolant level
• Filling the coolant

Preparations

1. Park the Volkswagen ID.4 on a level and secure surface.

2. Allow the electric drivetrain to cool down completely before proceeding → .

3. Open the hood carefully.

The coolant expansion tank in the Volkswagen ID.4 is identified by a red symbol on its cap → fig. 1.

Fig. 1 In the hood space: Cap on the coolant expansion tank (general example).

WARNING

Hot steam, coolant, and heated components in the Volkswagen ID.4 cooling system may cause severe burns.

• Never open the hood if steam or coolant is visibly escaping.
• Wait until all components have cooled and no steam is present before proceeding.

WARNING

The cooling system remains pressurized when hot. Opening it improperly may result in hot coolant being expelled, causing serious injuries.

• Never open the coolant expansion tank when the electric drivetrain is hot.
• Always protect exposed skin using a thick cloth when handling the cap.
• Slowly turn the cap counterclockwise while applying slight pressure to release any remaining pressure safely.

Checking the coolant level

Fig. 2 In the hood space: markings on the engine coolant expansion tank (general example).

When the Volkswagen ID.4 is new or after cooling system maintenance, the coolant level may be slightly above the marked range. This is normal and does not require adjustment.

In some configurations of the Volkswagen ID.4, the coolant level may not be clearly visible due to tank design. If you are unable to accurately determine the fluid level, consult a qualified technician. Volkswagen recommends contacting an authorized service center.

1. When the electric drivetrain is cold, check the coolant level against the markings on the expansion tank → fig. 2. The level should be within the indicated range.

2. If the coolant level is below the minimum ("min") mark, have the system refilled with the correct coolant mixture. When the system is warm, the level may slightly exceed the upper marking.

3. If no coolant is visible in the expansion tank, do not attempt to refill it yourself → .

Filling the coolant

1. Carefully and slowly unscrew the cap of the coolant expansion tank in the Volkswagen ID.4 → .

2. Only refill the cooling system of the Volkswagen ID.4 using coolant that fully complies with Volkswagen specifications (→ Engine coolant). This ensures optimal performance, corrosion protection, and longevity of the system.

If suitable coolant is not immediately available, you may temporarily top up with distilled water only. However, the correct mixture ratio with the approved G12evo coolant must be restored as soon as possible by an authorized Volkswagen dealer or authorized Volkswagen Service Facility. Volkswagen strongly recommends professional inspection and correction → .

3. Carefully fill the coolant until it reaches the upper marking on the expansion tank. After topping up, the coolant level in the Volkswagen ID.4 must always remain within the marked range → fig. 2.

4. Reinstall the cap securely, ensuring it is tightly closed to maintain proper system pressure.

5. After approximately one day, recheck the coolant level in the Volkswagen ID.4. If the level drops below the "min" mark again, have the cooling system inspected by an authorized Volkswagen service facility without delay.

6. If no approved coolant is available, do not use alternative or incompatible coolant additives under any circumstances → .

NOTICE

Coolant expands when heated. Overfilling the system in the Volkswagen ID.4 may cause excess coolant to leak out and potentially damage surrounding components.

• Never fill coolant above the upper limit marking on the expansion tank.

NOTICE

If the coolant expansion tank in the Volkswagen ID.4 becomes empty, air may enter the cooling system. This can lead to serious damage to the electric drivetrain.

• Do not continue driving the vehicle.
• Do not attempt to refill the coolant yourself in this situation.
• Contact an authorized Volkswagen dealer or service facility immediately.

NOTICE

Using non-distilled water can introduce harmful minerals and impurities, leading to corrosion and potential malfunction of the cooling system.

• Always use distilled water when topping up coolant in the Volkswagen ID.4.
• If non-distilled water has been added, have the cooling system completely flushed and refilled by professionals.

NOTICE

The use of incorrect or incompatible fluids in the Volkswagen ID.4 can result in serious malfunctions and long-term damage to the drivetrain and cooling system.

• Always ensure that only approved fluids are used for each specific reservoir.

Troubleshooting

Engine coolant

The red warning light in the Volkswagen ID.4 instrument cluster may begin to flash if the coolant temperature becomes too high or if the coolant level is too low.

Do not continue driving! Continuing operation may cause severe damage to the electric drivetrain of the Volkswagen ID.4.

1. Bring the Volkswagen ID.4 to a stop as soon as it is safe to do so (→ Parking).

2. Deactivate drive-ready mode to ensure the Volkswagen ID.4 cannot move unexpectedly.

3. Allow the electric drivetrain of the Volkswagen ID.4 to cool down completely before performing any further checks.

Engine cooling system

1. Check the coolant level in the Volkswagen ID.4 cooling system (→ Engine coolant).

2. If the warning light remains on even though the coolant level is correct, do not continue driving the Volkswagen ID.4; immediately deactivate the drive system.

3. Contact an authorized Volkswagen dealer or authorized Volkswagen Service Facility for professional assistance and diagnosis.

together with High-voltage coolant system malfunction

The warning indicators in the Volkswagen ID.4 will flash red, signaling a critical issue within the high-voltage cooling system.

Do not continue driving!

1. Stop the Volkswagen ID.4 immediately in a safe location (→ Parking).

2. Switch off drive-ready mode without delay.

3. Contact an authorized Volkswagen dealer or service facility immediately, as this condition requires urgent professional attention.

Introduction

Brake fluid in the Volkswagen ID.4 is a critical safety component that gradually absorbs moisture from the surrounding air over time. Excessive moisture content can significantly reduce the boiling point of the brake fluid, which may lead to vapor formation (vapor lock) during heavy braking. This condition reduces braking performance, increases stopping distances, and in extreme cases can result in complete brake failure. The proper functioning of the brake system in the Volkswagen ID.4 is essential for your safety and the safety of others on the road.

WARNING

Brake fluid is toxic and hazardous. Contact with brake fluid, especially ingestion, can result in serious or fatal injuries.

• If brake fluid is swallowed, seek immediate medical assistance.
• If you feel unwell after handling brake fluid, consult a healthcare professional.
• Always store brake fluid securely in its original sealed container and keep it out of reach of children.
• Never transfer brake fluid into food or beverage containers.
• Avoid prolonged skin contact with brake fluid.
• Use protective gloves and eye protection when working with brake fluid in the Volkswagen ID.4.
• Do not eat, drink, or smoke while handling brake fluid.
• Wash exposed skin thoroughly with soap and water after contact.

NOTICE

Brake fluid spilled on the Volkswagen ID.4 can damage paintwork, plastic components, and tires.

• Immediately clean any spilled or leaking brake fluid from vehicle surfaces.
• Rinse affected areas thoroughly with clean water.

Brake fluid used in the Volkswagen ID.4 can be harmful to the environment. Always collect and dispose of any waste fluid in accordance with local environmental regulations.