How do you replace check engine light bulb ours has burnt out?

You don't replace a "check engine light bulb." The "check engine" light isn't a bulb in the traditional sense; it's an indicator light controlled by the vehicle's onboard computer. A burnt-out "bulb" indicates a problem with the light itself, or more likely, a problem with the vehicle's electrical system related to that light.

Instead of trying to replace a bulb (which you can't easily do on most modern cars), you should:

1. Check the fuse: The check engine light circuit is protected by a fuse. Consult your vehicle's owner's manual to locate the fuse box and find the fuse responsible for the check engine light. Replace the fuse if it's blown.

2. Inspect the wiring: Look for any loose, damaged, or corroded wiring connected to the check engine light. If you find any issues, you may need to repair or replace the wiring. This is best left to a qualified mechanic if you're not comfortable working with car wiring.

3. Have the car scanned for codes: The check engine light illuminates when the onboard diagnostic system (OBD-II) detects a problem. A mechanic or auto parts store (they usually offer this service for free) can use an OBD-II scanner to read the diagnostic trouble codes (DTCs). These codes will pinpoint the issue causing the light to come on. Addressing the underlying problem will likely resolve the light issue as well.

In short: Don't focus on replacing a nonexistent "bulb." Focus on diagnosing and fixing the reason the light isn't working (or more importantly, the reason the engine light is on in the first place). A mechanic is the best resource for resolving this situation if you're not experienced with automotive repair.