General information

✓ Valid for: Mild Hybrid vehicles (MHEV)

Fig. 243 48-volt battery: hazard warning

1. Never expose the 48-volt battery of your Seat Leon to sources of fire, sparks, or unprotected open flames.
2. The official vehicle instruction manual and specialized workshop technical documentation contain further critical information and safety warnings regarding this high-voltage component.
3. Always keep children far away from the 48-volt battery housing area.
4. If the 48-volt battery casing is structurally damaged, internal fluid can leak out and form highly corrosive acids. For this reason, the battery should only ever be handled by trained, qualified technical personnel.
5. All maintenance, repair, or inspection work involving the 48-volt battery system must be performed exclusively by duly qualified and certified technical staff.
6. Exercise extreme care when handling inflammable substances or hazardous materials near the vehicle's electrical architecture.

In addition to the standard 12-volt battery, Mild Hybrid variants of the Seat Leon are equipped with an advanced 48-volt lithium-ion battery neatly positioned underneath the front passenger seat.

Any technical work that needs to be carried out on the 48-volt battery system must be executed exclusively by a specialized workshop staffed by qualified technicians who have been specifically trained according to official SEAT guidelines.

Overview of the 48 volt system

The 48-volt mild hybrid system consists of the following key high-voltage components, among others:

• 48-volt lithium-ion battery unit
• 12V/48V DC-DC voltage converter
• 48-volt belt-driven alternator-starter motor
• Distinctive purple-colored 48-volt high-voltage electrical cables

48 volt battery warnings

A prominent hazard warning sign is affixed directly to or near the 48-volt battery to alert occupants and technicians to potential electrical risks ››› Fig. 243.

WARNING Inappropriate or unauthorized handling of the 48-volt battery can cause severe personal injuries or even fatal electrical accidents.

• All service and maintenance work involving the 48-volt battery must be performed exclusively by duly qualified and certified technical staff.
• Never make any modifications, alterations, or unauthorized changes to the 48-volt battery system.

WARNING Always ensure that the 48-volt battery and its surrounding wiring do not come into direct contact with water, moisture, or any other fluids.

• Liquids entering high-voltage electrical components can cause dangerous short circuits, severe electric shocks, and chemical burns.

Troubleshooting

✓ Valid for: Mild Hybrid vehicles

Instrument cluster control lamps and driver warning messages displayed on the dash panel or infotainment screen:

48-volt battery

The indicator lamp lights up in bright RED. The following critical emergency message is displayed: Battery: Risk of fire! Stop safely and get out quickly. Call the emergency services.

The internal temperature of the 48V battery has exceeded safe operational limits.

If this emergency message appears on your Seat Leon instrument cluster, execute the following steps immediately:

• Stop driving! Bring your vehicle to a complete stop immediately, taking careful account of the surrounding traffic situation and road safety.
• Choose a safe location outdoors, positioned well away from buildings, structures, other vehicles, awnings, covered multi-story car parks, or similar enclosed structures.
• Switch on the hazard warning lights immediately.
• Before leaving the vehicle, make sure it is completely immobilized (engage the electronic parking brake and select the P parking lock).
• Switch off the ignition completely and leave the ignition key on the dash panel or in a visible location so that emergency responders can easily access it if needed (for example, to recover the vehicle from a hazardous zone).
• Exit the vehicle promptly and make sure that no other passengers or pets remain inside.
• Ensure that you leave the danger zone together with all other vehicle occupants and that everyone moves to a secure area fully protected from ongoing traffic (such as behind a roadside safety guardrail).
• Notify the emergency services immediately.

48-volt battery

The indicator lamp lights up in red while driving.

The following warning message is displayed: Error: 48V power supply. Stop safely! Please refer to the instruction manual.

An active system error has been detected within the 48V power supply architecture.

1. Park your Seat Leon safely in a secure location.

2. Stop the engine and turn off the ignition.

3. Wait for a few seconds.

4. Switch the ignition back on.

5. Restart the engine.

If the warning lamp remains illuminated, seek professional technical assistance without delay.

SEAT recommends visiting an authorized SEAT dealership for professional diagnosis and repair.

48-volt battery

When the vehicle is stationary, the warning lamp lights up in yellow and the following message is displayed: Error: 48V power supply. Do not start driving.

Please refer to the instruction manual.

A fault has been registered in the 48V power supply network.

1. Park the vehicle in a safe place.

2. Stop the engine and turn off the ignition.

3. Wait for a few seconds.

4. Switch the ignition back on.

5. Start the engine.

If the warning light stays on, seek professional assistance immediately.

SEAT recommends visiting an authorized SEAT dealership for this.

48-volt battery

When the vehicle is stopped, the indicator lamp lights up in yellow and the following message is displayed:

48V battery charge low. Start the engine or refer to the owner's manual.

48V Battery state of charge warning alert.

1. Start the engine of your Seat Leon.

2. Stand safely stationary and leave the engine running for a few minutes to allow the mild hybrid system to recharge.

If the indicator lamp remains on, seek professional assistance.

SEAT recommends visiting an authorized SEAT dealership for this service.

If the engine cannot be started:

1. Switch the ignition off.

2. Utilize the emergency jump-start procedure.

If the vehicle still fails to start up, seek professional technical assistance. SEAT recommends visiting an authorized SEAT dealership for this purpose.