ok so my catylac converter broke the other day so i had some guy weld it back and he never unscrewed the o2 sensor and welded it while it was still attached and i guess fried it cause now i have a check engine for it and it says no activity detected or something.... my question is what problems would this cause to my car? its been like stuttering or not responding when i hit the gas peddle and this started after this happened im wondering if this would casue this... please let me know if its something i should fix asap.. thank you

 

uh... yes.

If you paid that guy, then he should be responsible. Complain.

 

yea but a bad o2 sensor isnt going to make ur car stutter everytime u hit the gas... i have 2 bad o2 sensor codes popping and my car drives fine.. i was thinking if u cant accelrate or it stutters when u hit the gas then i would think MAF sensor.. but i could be wrong

 

its not everytime i hit the gas, just sometimes when im in first i go to give it more gas and nothing happens and it like goes in and out its weird.... ill look into the maf sensor more i think that code came up before but hasnt in a while..

 

Yes, it absolutely can. O2 sensor is VERY important. More important than the MAF, even.

 

well must not be that bad cuz i have 2 that are bad and the car still drives fine other than occasional rpm drop at idle

 

Then yours aren't all THAT bad.

 

well i dont remember the code numbers, but i remember one of them said something like no data return from side 1 bank 1 or some **** like that... so one of them isnt even being registered to the ecu

 

I had a bad bank 2 O2 sensor on my 01 A4 2.8 and it would do the same thing. I would be driving a constant speed and let of the gas and coast a little, like if the car in front of me was turning off the road, and as soon as I got on the gas again it would stutter.
You're lucky you found someone willing to weld you're catalytic converter, most shops aren't willing to go anywhere near them. When mine separated at the turbo flange on my 1.8t a4 I took it to numerous shops and they told me they legally could not weld or repair a cat, I even took it to my friends shop and he wouldn't do it!

 

if you ever weld on a car make sure you disconnect the battery... when i was in iraq and welded on alot of vehicals when i was in the army. i had to make the crew of the truck disconnect the batterys and radios before i would even touch their truck. a few times the crew would be lazy and tell me they did it when in reality they didnt. i welded up some armor and slat metal and then they would get in and find out that their batterys where toast and the ecm was junk so i mean just somthing to think about in the future i know humvees and strykers arnt made by audi lol but still its common scene to do this when your adding a shitload of current and what not to metal with sensors and **** conneceted to it.