2004 chevrolet blazer 4 x 4

I have a 04 chevy bazer 4x4 my check engine light at times comes on.
what type of data scanner can I buy that will fit my blaser so I can scan it? Mike

Any OBD11 code reader will read OBD11 codes.
But do not get into other systems or codes.
A lot of parts places will read OBD11 codes for free.
But do not buy the parts they try to sell you for that code.
Post back code no and someone will help you.
But remember codes do not say replace the part.
They only point you in the right direction.
You will need to go threw the repair flow chart for that code.

If a flashing check engine light you have a missfire.

What engine and what mileage on you tune up end?