It has been a long time since lighting repair was a guaranteed easy, quick repair.
While simple bulb replacement may still be straightforward (or not depending on how easy they are to access), HID lighting systems will often require an overnight stay for your four-wheeled guest.
This may not be what a customer is expecting with a “simple” headlight replacement—something the service advisor should be clearly communicating—but the considerations for the tech do not end there.

1. If the headlight assembly shows any sign of damage (water or dirt intrusion), make sure the entire assembly is replaced prior to replacing the ballast.

2. When servicing an HID system, make sure the Headlight Level Sensors are working properly. They are essential to proper performance of an HID lighting system.

3. If the vehicle has been in a collision or the ballast is burned out, ensure that proper voltages and grounds are present at the new ballast. Low voltage or a weak ground will damage the new unit.

4. Use caution not to touch the HID bulb. Due to the high operating temperature of the bulb, oil from your fingers can cause damage. If you’ve touched it, use rubbing alcohol to remove the oil from the bulb

5. In many cases, if the bulb is burned out, the ballast may be damaged, too.

6. Proper input and output testing should be performed prior to quoting the job to the customer.

SPECIAL CREDIT TO Standard Motor Products for inspiring this tip.