Do I need any special tools or adapters to install these?

These mount directly at the factory sensor bungs with no adapters needed. You'll want an oxygen sensor socket (a cheap, standard tool) and basic hand tools. Disconnect the battery before you start and let the exhaust cool completely—sensor bungs sit in hot territory.

Will these trigger a check engine light?

Not if they're installed correctly and functioning properly. If your light was on before install due to a bad sensor, it should clear once the new sensors complete their readiness cycle—typically after 50–100 miles of normal driving.

Can I install just one sensor, or do I need both?

You can replace one at a time if needed, but both sensors work together to balance fuel trim across both banks. Replacing the pair ensures consistent engine performance and prevents uneven air-fuel ratios between cylinders.