1999 Tahoe Engine Code 430 and 442

Ive drilled them out with a 1/2 inch drill bit and the sensor still wont fit through it enough for me to screw them in. What size drill bit did you use, Im afraid to go much larger as I dont want to mess up the threads.

 

Isn't the muffler after the catalytic converter? Why would a muffler cause the system to detect a malfunction from the cat? Maybe the cat was already on the way out?

As for the EVAP code, this is not related to the exhaust system at all. It's probably just a coincidence it came on. I think gas tank cap would be a common issue setting this code.

 

Yup, 90% of the time you tighten the cap and erase the code.

* BUT *

As a tech I always checked the evap canister. If I tapped on it and it sounded hollow, it was good. If it made a thud, it was usually full of gas. If you always fill your gas tank to the tip top where it won't take any more gas, you're filling your evap canister. When the gas pump clicks off, call it done.

 

My K3500 had a problem where it wouldn't take gas in even if empty. No SES codes.

Once I was messing with my GMT800 SES EVAP code and I watched a video on testing the purge solenoid with a handheld vacuum pump...I was curious on my other trucks and happened to test the K3500 and it was actually faulty (wouldn't purge (open) with a 12VDC jumper.) I changed it and it is all good...but in retrospect, isn't the vent solenoid that would cause this issue with the filling gas tank?

I still haven't figured out the GMT800 small leak code, LOL. Smoke machine passed...aargh!

 

I don't have an OBDII GMT400 any more, so I don't know where the solenoid is, but I'm pretty sure that if you continually overfill into the neck some of that gas is going to get into the evap canister and eventually fill it.

 

Never had to drill them out. The ones you buy at the auto store you do need to drill, but the ones on ebay have a through hole the correct size of the o2 sensor

https://www.ebay.com/itm/4x-O2-Oxyg...4bb28e257778c334b8a1|ampid:PL_CLK|clp:2334524