That might work for getting the thinner through the system but don't bother trying it just to see if you get the code to come back after resetting it. Even driving 100 miles is just an estimate. Once you reset the system monitors (sensors) by disconnecting the battery, etc., they have to complete a "drive cycle" before they will start giving codes again. Just letting it sit won't do that. I don't know what the exact drive cycle is for our trucks but they are always something wacky like, idle for 5 minutes, then drive 20 miles at between 30 and 40mph, then sit and idle for 5 minutes, and then drive 30 miles at between 50 and 60mph - stuff like that.

Do you have an OBD-II scan tool? With most scan tools, you can see when each monitor is "ready" which means it has completed a cycle. When I installed the new sensor on my 4runner, I knew what the cycle was and tried to replicate each step and still had trouble getting everything to show a completed cycle. I really ended up just having to wait for it to happen naturally.

 

How much does a cat cost? also if it is the cat,am i hurting anything to drive it... can't afford a garage bill right now...getting average gas milage with or without the check engine light on.. truck runs great,except seeing it on...(engine light)

 

Not sure how much a CAT is but it is a sure bet it is much more expensive than a sensor. And if the issue is only the sensor, replacing the CAT wont fix the code problem. I would try the sensor first if no leaks are found. Worse case, you have to buy a CAT in the end and you have a new sensor to go with it. By the way, dont buy a Bosch sensor.

It shouldnt hurt anything in the short term to drive it like it is until you get it all worked out.

I will also add that my mother in law also recently had a similar situation in her GM product. Different code from the upstream sensor but the code did not indicate that the issue was the sensor itself. I replaced the sensor for her and her problem went away as well. Sensors wear out just like other parts do so it is not far fetched that issues like this are just a sensor and not the actual parts the sensors indicate.