96 Ranger, check engine light

[RDNaugle]

I have a 1996 Ranger with about 50,000 miles. A couple of months ago the Check Engine light stayed on and the truck ran rough with spark knock. I had it checked to find a bad EGR. EGR and control module were replaced and codes were cleared. On second start up the check engine light came back on but truck runs good. Have had codes rechecked and it showed no problems but on second start up the check engine light comes back on. I have tried many times to disconnect battery to clear the codes and as always the check engine light turns on with the second start up. Has anyone else had this problem?

Thanks

[blkcavi02]

most likely it is the spark plugs or 02 sensor

[jasons_97Ranger]

I would say the 02 sensor. most likely the one right after the catalytic converter. my '97 has the same problem.