I had to unhook the battery in my 04 TL and at the same time I swapped the front upstream o2 sensor.

So, far I drove the car about a 100 miles & got gas - no CEL light, but it still does not come back as ready either.

Any input would b appreciated - I looked everywhere & found nothing concrete.

The only thing that is showing not ready is my EVAP

 

the system takes some time to get going after you pull the battery

 

How many miles are we talkin here, approximately?

 

Some cars take 150+ miles. Hook up a scanner to see if it's ready.

 

There are specific conditions that you need to meet in order for EVAP cycle to complete successfully. I had the same issue when I got random misfire CEL. I had to do emission test so I erased the code and could not get EVAP system to complete. I found out that in Illinois you can pass emission test with 2 specific cycles incomplete. One of them was EVAP system so I passed the emission test with EVAP inc :-) It took about 100 miles for it to complete in my case. It all depends on your driving habbits.

Here is the info from another thread. That is probably your full driving cycle:

"The vehicle should be driven approximately 7.5 miles within a period of approx. 23 minutes (1372 seconds) from a cold start. However, due to manufacture variations, it is necessary to perform only as much of the Drive Cycle as is necessary to reset the required monitors to a "Ready" status. Operate the throttle smoothly to obtain best results. Do not shut the engine off during the drive cycle.
Step 1 (Engine Cold) Start engine, idle 20 seconds. Accelerate gradually and drive at 20-25 mph for 1 minute, varying speed.
Step 2 Accelerate gradually to 32 mph within 35 seconds. Decelerate to 0 mph in 10 seconds. Idle for 40 seconds.
Step 3 Accelerate at part throttle to 25 mph in 10 seconds. Cruise at 17-25 mph for 15 seconds. Accelerate gradually to 57 mph in 45 seconds. Cruise at 50-56 mph for 1 minute. Decelerate gradually to 0 mph in 40 seconds. Idle for 15 seconds.
Step 4 Accelerate at part throttle to 36 mph and maintain for 10 seconds. Decelerate to 0 mph in 15 seconds. Idle for 5 seconds.
Step 5 Accelerate to 30 mph and back to 0 mph within 30 seconds. Idle for 20 seconds.
Step 6 Accelerate to 36 mph in 20 seconds. Drive at 35 mph for 20 seconds. Decelerate to 0 mph in 15 seconds. Idle 5 seconds.
Step 7 Accelerate gradually to 26 mph and decelerate to 0 within 40 seconds. Idle 15 seconds.
Step 8 Accelerate to 27 mph in 40 seconds. Decelerate to 0 mph in 10 seconds. Idle 25 seconds.
Step 9 Accelerate to 26 mph in 15 seconds, maintain speed for 10 seconds, decelerate to 0 mph in 10 seconds. Idle 15 seconds.
Step 10 Accelerate to 23 mph in 20 seconds, decelerate to 0.5 mph in 10 seconds (no complete stop). Accelerate to 28 mph and back to 0 mph (momentary stop 1 second) within 35 seconds.
Step 11 Accelerate gradually to 34 mph in 45 seconds. Vary speed between 34 and 19 mph for 2 minutes. Decelerate from 25 to 0 mph in 25 seconds. Idle for 5 seconds.
Step 12 Accelerate to 29 mph in 15 seconds, decelerate gradually to 0 mph in 45 seconds. Idle for 30 seconds.
Step 13 Accelerate gradually to 28 mph and back to 0 mph (momentary stop 1 second) within 50 seconds. Accelerate gradually to 27 mph and back to 0 mph within 55 seconds. Idle for 15 seconds.
Step 14 Accelerate to 24 mph and back to 0 mph within 18 seconds. Idle for 10 seconds. Accelerate gradually to 22 mph and back to 0 mph within 50 seconds. Idle for 8 seconds.
Step 15 Accelerate gradually to 30 mph within 50 seconds. Decelerate to 0 mph in 10 seconds. Idle for 25 seconds.
Step 16 Accelerate to 23 mph and back to 0 mph within 30 seconds. Idle for 10 seconds.
Step 17 Repeat steps 1 - 16 once again. Recheck the status of the "Readiness Monitors".

NOTE: Remember, clearing DTC's or interrupting power to the ECM after the readiness monitors have been reset to "Ready" will require that the Drive Cycle be repeated.

Completing the Drive Cycle successfully one (1) time should reset most drive cycle monitors to a "Ready" status. However, there are "two trip" monitors, which require that the drive cycle be successfully completed two (2) times, to achieve a "Ready" status. Furthermore, systems which use averaging, may require the drive cycle to be completed more than 2 times. It is necessary to perform only as much of the Drive Cycle as is necessary to reset the required monitors to a "Ready" status

"this is taken directly from alldata" i always do this and have never had any issues. if this doesnt work then you might have some problem with the computer losing power after you shut the vehicle off. i have never been unable to get the monitors set within 25 mins or so of driving unless its a dodge van or truck which some of them take like 60 warm up cycles to complete. hope this helps"

 

Well, I looked up the emissions testing specs in AZ - you can have one not ready & pass

On the day I was going to take my car in - the CEL popped on again for the same thing - p2197 - front o2 sensor

So, long story short - I removed the PCM fuse, then took off on the freeway for about 40 miles, all parameters were ready except for the Evap. Took it straight to the emissions station & passed with flying colors.