manual check engine light on 2000 Pontiac Bonneville

How to manually check the codes for check engine light

you need a code reader. no other way.

even a reader will not tell you the failure, just the system failure.
let a shop do a real diag for you.

Thanks, some can access trough cars chip on dash...
chrysler can be done by cycling the ket 3 times but does not translate the code into terms we know without a manual. they are the only ones.