How long till codes clear?

1997 XJ, 4.0, stock engine, etc. Had some issues with the exhaust over the past couple of weeks, ended up replacing the down pipe and catalytic converter, and two oxygen sensors. Last week I ran it without the rear O2 sensor in place, got a check engine light after about 100 miles. Finished installing the new cat and O2 sensors today, backed it out of the garage, CEL is still on.

Does this take a few miles to clear or do I have another fault? I figured I'd start out by fixing what I knew was broken.

I had a stumbling issue at high rpm's last night while accellerating on the highway, trans kicked down, revs went to 4000, engine stumbled, trans kicked up a gear in response. I thought I was going to stall out when it stumbled, I was half way through an "aggressive lane change" and had to abort. This is after running 500 miles or so without the downstream O2 sensor. Related? I recreated the stumbling later on the highway, couldn't get it to do it by revving unloaded (parked) after doing the O2 sensor.

Thoughts?

Thanks,

Mark

Did you have the codes checked yet? After you get them read, and find out what they mean, have them erased/deleted. They do not just disappear by themselves.

Nope, I've not cleared them - I was hoping they'd clear themselves. The CEL was off for about half of my morning commute mid week last week, I don't know if it forgot, or what. I'll hit the auto parts store tomorrow after work and see if they can do it for me.

Thanks,

Mark

Disconnect the battery cables then hold the ignition key in the start position for about 30 seconds. Reconnect cables and the codes should be cleared. Don't try to take it in for emissions or something right away though, as the computer takes some time to store a new data set and will show as not ready.

OK, I broke down and bought a code scanner, cost me $135, and I cleared the codes. The code that was in there was an error on my rear oxygen sensor, I replaced the unit this weekend so I'll see if the new one is doing what it should or not.

thanks,

Mark