high idle engine light on but no codes

What is your question?

i have a 99 galant 2.4l 4 cyl. i turned it on this morning and it started to idle high. the service engine light came on and i took it to autozone and advanced auto to scan but they couldnt retrieve any codes nothing was showing up. i did realize i have an ignition coil which should be replaced because i had to reassemble it . any help would be greatly appreciated