I have a 2003 Chevy 1500 4.8L Vortec with the 4L60-E transmission. I searched the forum and made sure no one else was having this problem so not to clutter the board, and could not find anything.

Here is my problem.

Truck drives perfect for about 2 miles, then trans feels like it starts to slip going from gear to gear for another mile, then it will not move any. It will just sit and rev up. If you park the truck, shut it off completely, and restart it, it will work fine for the next 3 miles until it will not move again.

I have read that the O2 sensor and trans are on the same fuse, and the check engine light is on. The guy at Auto Zone gave me the Po420 code which means either o2 sensor or catalytic converter problems. Would this maybe have something to do with it?

Anyone else ever have this problem?

 

if your o2 sensors are bad or going bad yes it will cause our truck to lack the power needed also same with the cats if yoru cats are pluged there will be to much restriction on the exsaust and the engine cant produce enaugh horse power or torque needed the o2 sensor works by sensing how much fuel air mixture is in yoru exsuast and will tell the computer how much or how fuel is in your exsaust it is an emisions thing hell cars in the 60 and 70s didnt even come with them if they are bad it will tell the computer theres to much gas or to little gas and the computer will go nuts tryign to guess on its own when the o2 sensors should be working
i would suggest going to another auto parts store like oriellys they allow you to barrow the obd2 scanner and you can scan it yourself to see what codes im not saying hes wrong but i would do it for myself but thats just me
also it could be a shift soliniod or lack of trans fluid i believe on your year of truck you can scan the transmission with the same obd2 scanner if its not a cheap on if it is the trans slipping the bands are worn out inside the transmission and you can rebuild but for the price of a rebuild you can geta new one also check the vacum lines if theres a leak it can cause your truck to run really goofy

hope this helps

 

thanks man.

Do you think if I unplugged the o2 sensors that it might show me that that might be causing it?

Will unplugging them make the truck run even worse?

 

i wouldnt recomending to take them out just to test them as there a pita to get out i had to use a torch to heat them up on my 94 i used to have
if they are bad there wlould be a code thrown for it
which you did mention but i would go in depth further by useing the scanner and running your own test after the codes come up right them down sometimes you have to go in search for the codes as they dont allways show up on the first one then delete the codes and see what ones come back