my BMW 3 Series E90/E91 (2005-2012) headlights are flickering, what should I check?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the vehicle battery to ensure safety while working on the electrical system.

2. Inspect Headlight Bulbs

• Remove the headlight assembly cover by unscrewing the retaining clips or screws.
• Carefully pull out the headlight bulb and visually inspect it for any signs of burning or damage.
• Replace the bulb if it appears faulty. Ensure you are using OEM or high-quality replacement bulbs.

3. Check Wiring and Connections

• Visually inspect the wiring harness connected to the headlights.
• Look for any signs of wear, fraying, or corrosion on the connectors.
• Clean any corroded connections with electrical contact cleaner and reassemble securely.

4. Test and Replace Relay

• Locate the headlight relay in the fuse box (refer to owner's manual for exact location).
• Use a multimeter to test the relay for continuity. If defective, replace with an identical relay.
• Reinstall the relay and ensure it’s seated properly.

5. Inspect and Test Battery and Alternator

• Reconnect the battery and use a multimeter to check the battery voltage.
• Start the engine and check the voltage output from the alternator. If the voltage is low, consider replacing the alternator.