Check engine light on 2006 Chevy Trailblazer?

That is because the "Garage" Improperly diagnosed the problem! However, you will need to provide more information than you have, Take the vehicle to an auto parts store and ask if they could scan your vehicle for stored codes (and write the code NUMBERS down on a piece of paper) and update your findings!

ALSO, Is there any drivability issues? (stalling, hgard starting, rough running, hesitation, etc)

NOTE: Most common issue on the Trailblazer to illuminate the CEL (check engine light) is a P0106 for an excessively carboned up ETB (electronic throttle body)

2006 Chevy Trailblazer...my check engine light came on after the tighten gas cap came on. I replaced gas cap and the light is still on. It had already passed emissions 3 days before this problem, can you tell me what should i do to fix this problem?

I would suggest that you contact your local Chevrolet dealership and have them look into this for you. They are in the best position to get this issue properly diagnosed for you. If you have any further questions please feel free to contact me.

Thank you,

Stacy GM Customer Service

go to a different shop...but first get it scanned at your local autozone or advanced auto, they will scan it for free and narrow the problem down for you, then go to a different shop and have it fixed there, better yet go to the chevy dealer.

...and you can't tell us the code nor the part replaced.....brilliant.

Come back with some actual info.