Does anyone know what these trouble codes mean?
EO46
IO39
IO52
ao48
NO SIR CODES
ECM?
This is how they are displayed on the dash.
This is for a 92 Eldorado with 4.9L
Thank you

Also what is the best way to change plugs? looks like the front ones are easy but what about rear? maybe from underneath?

Click on Search and do an Advanced Search.

Put "How can I check for any codes Im throwing" in the titles search and put "RAMAIR57" in for the user name. That post has all of the codes you listed except EO46 defined.