i won a 97 zj 4.0

Check engine linght lit up checked it out with the codes a misfire #6. changed the pluges and wires. ran fine and the light turned off. a week later Check engine back on ran the codes agin a misfire #6 and bad O2 sensor, replaced both O2 sensors the light did not turn off. took it to a shop and they told me the same thing they erased the codes for me. when i got it back the check engine light was off and runing fine. and now today i ran codes to see if the misfire was still there.and yes both the old codes came up bad O2 and missfire. i erased them and they have not came back. but it still sounds like its mising on a cylinder. so i took off #5 wire let the car run turned the car off ran the codes and nothing. :banghead: so should the light come on every time there are codes or new ones to the list :uhoh:

i won a 97 zj 4.0

Check engine linght lit up checked it out with the codes a misfire #6. changed the pluges and wires. ran fine and the light turned off. a week later Check engine back on ran the codes agin a misfire #6 and bad O2 sensor, replaced both O2 sensors the light did not turn off. took it to a shop and they told me the same thing they erased the codes for me. when i got it back the check engine light was off and runing fine. and now today i ran codes to see if the misfire was still there.and yes both the old codes came up bad O2 and missfire. i erased them and they have not came back. but it still sounds like its mising on a cylinder. so i took off #5 wire let the car run turned the car off ran the codes and nothing. :banghead: so should the light come on every time there are codes or new ones to the list :uhoh:

Usally the error has to happen in 3 driving sesions for the code to be logged...