I just bought a 2001 Oldsmobile Silhouette Premier. 160k on the Odometer. Lots of service history: trans, intake, a folder full of oil changes, etc.

When I bought it, the battery was dead. It took awhile to jump and ran well if I didn't use any electronics but wouldn't restart if I turned it off. So I replaced the battery.

I did this right before I took it to get smogged. It passed the exhaust test but when hooked up to the OBD II it failed everything but did not show a "Check Engine" or "Service Engine Soon" light. First thing the tech asked if I had changed the battery recently.

(I should interject that I do have a couple lights on the cluster, ABS and Trac Off and when I start the car I get a Change Oil Soon and a Service Traction Control")

He said the computer needed a little while to reset and I should drive it around for about 30 to 50 miles and come back. I hit the road and put about 45 miles on it and returned. He said that most of the systems had reset but it was still reading an E-vap and another code (I don't remember which one) but still no CE or SES light on the cluster which was a good sign.

It was late so I got on the freeway and put another 50 miles on it with the intent of taking back in the morning. Still no Check Engine or Service Engine lights. I got called into work so I had my wife take it back to the smog shop. She called to say it was still throwing codes. She had the day off and decided to drive around, run errands, and drive up to the foothills to see some friends. she put another 120 miles on it. Took it back to the shop and its still throwing codes.... The Shop owner said we should try lots of cold starts; Start up the van, drive until its at operating temp, turn off car and left it cool down, rinse and repeat.

Is this normal? Any suggestions? Thanks.

Is it actually throwing codes, or just indicating that the tests are not ready? If so, are the codes pending, or fully set? What code numbers are we dealing with?

That'* a good question. I'll ask when I try again tomorrow. He showed me a paper the first time that had a ton of stuff like evap, o2, etc when he asked if I had just changed the battery. Now that I think of it, I think he said it wasn't ready. When I took it back he said it'* still showing the evap and something else (I don't remember) but I think you might be right, the system wasn't ready.

I'll ask tomorrow and report back.

Anytime you disconnect the battery on a 1996 or newer vehicle, it resets the readiness monitors. This should be completely avoided unless absolutely necessary when you are close to inspection time.

To avoid losing memory functions, you can use a power saver before disconnecting the battery.
The one I have is an OBD2 cord at one end, and is powered by plugging into an accessory socket, on a jumper/power supply box.

I'm so use to working on old cars, it'* probably my number one hobby. I'm in the middle of two builds right now, a 61 Tbird and a 70 Dart Swinger, but I am always surprised how little I know about modern systems.

I'm taking it back to the smog guy today. When my wife took it there on Wednesday, the tech said that we were waiting for one last system to reset, something about a system that controls the air intake on cold starts. I guess it has to cycle through a few cold starts before it resets. Since we have just been driving it without many cold starts, that system hadn't reset yet. We'll see today.

Yeah, Mike has nailed it....if you disconnect a battery, or, clear codes with a scan tool, this resets the emission flags....You have to have a proper "drive cycle" run, in order to make each flag, run a test, and then if that test has run and passed, your flag is reset.......

Some flags run/pass very quickly, others take time....

A drive cycle that has worked for me is this:

Start the vehicle(cold) in the morning....leave it in park until it reaches normal operating temp.....

Now take it out on the highway, and SAFELY drive it this way....accelerate to 65 MPH, then let it cruise down to 4o mph...then repeat, several times.....now pull off the highway, come to a complete stop, shut vehicle off....wait 5-10 seconds, restart the vehicle, turn around and get back on the highway, and do the accel/decel thing again......this usually takes care of the drive cycle.......

It passed today. Which was the first hurdle, now onto the ABS / Trac Off lights. I'll do some searching on the sight before i ask questions.

Thanks you everyone who took the time to comment on this thread.