Check engine light intermittent

[shumthisway]

Alright so I'll have a check engine light seemingly randomly come on and eventually clear on its own. Codes are P0431 and P0421. I know its a code for a cat/02 sensor, I replaced both 02 sensors on that bank with NTK sensors. I've had issues with one of the bolts connecting the cat to the manifold coming lose which I thought was the original problem... I really dont wanna buy a new cat. What are some ways forward/things to look at? Also, I already hooked my shop vac up to my exhaust and used some soapy water to look for leaks/cracks which is what pointed me towards the bolt that wanted to come loose.

 

[JKP]

Mine has always been caused by loose cat to manifold bolts.

 

[macleanflood]

Never discount bad wiring, loose connections, corroded battery and ground terminals.

But...yeah...

-Mac

 

[shumthisway]

Never discount bad wiring, loose connections, corroded battery and ground terminals.

But...yeah...

-Mac

Negative battery terminal was pretty corroded. Let's see if that helps..

 

[shumthisway]

Mine has always been caused by loose cat to manifold bolts.

Ya ever find a way to keep it tight?

 

[Chris]

Ya ever find a way to keep it tight?

Try nylon loc nuts.

 

[macleanflood]

Try nylon loc nuts.

Nylon next to heat? Maybe a stover nut... maybe even a flanged one...

-Mac

 

[Chris]

Nylon next to heat? Maybe a stover nut... maybe even a flanged one...

-Mac

Oh yeah, that's a good point you've got there. I didn't think about that.

I was going to suggest loctite but that's probably a bad idea too given how hard those bolts can be to get off with some age.

 

[macleanflood]

I was going to suggest loctite but that's probably a bad idea too given how hard those bolts can be to get off with some age.

Frankly I consider all exhaust bolts expendable and usually just cut them off.

-Mac

 

[Chris]

Frankly I consider all exhaust bolts expendable and usually just cut them off.

-Mac

I agree. I always use anti-seize when putting new ones on though, always.

 

[JKP]

Ya ever find a way to keep it tight?

Just tighten it a few times in a row, then it's good for awhile. It's the only exh connection that I have dealt with that loosens instead of rusting together.

 

[macleanflood]

I agree. I always use anti-seize when putting new ones on though, always.

Antisieze is great until everything gets loose on the trail...control arms wiggle loose moving the pinion up causing the shocks to bend and fail...plus half the tub bolts fell out and the track bar bolt...I'm a red or blue loctite person from here out...


View: https://youtu.be/g0gGZee8BYQ?si=vr5Yv69YdfVEDQwO

-Mac

And P.S. my exhaust fell apart driving the WABDR...it dropped the body of the O2 sensor on to my clutch line and melted it in half!


View: https://youtu.be/fyh83tevZdY?si=sSjLq5cnAV0PF5M7

 

[Chris]

Antisieze is great until everything gets loose on the trail...control arms wiggle loose moving the pinion up causing the shocks to bend and fail...plus half the tub bolts fell out and the track bar bolt...I'm a red or blue loctite person from here out...


View: %5BURL%5Dhttps://youtu.be/g0gGZee8BYQ?si=vr5Yv69YdfVEDQwO[/URL]

-Mac

And P.S. my exhaust fell apart driving the WABDR...it dropped the body of the O2 sensor on to my clutch line and melted it in half!


View: %5BURL%5Dhttps://youtu.be/fyh83tevZdY?si=sSjLq5cnAV0PF5M7[/URL]

Damn...I guess the trail is a good way to really test everything out. I suspect on a street vehicle you'd probably be fine, but the trail is different. Thanks for sharing this!

 

[macleanflood]

Damn...I guess the trail is a good way to really test everything out. I suspect on a street vehicle you'd probably be fine, but the trail is different. Thanks for sharing this!

I think I'd rather have things fall apart crawling on a trail rather than doing 70 mph down the freeway...

-Mac

 

[Chris]

I think I'd rather have things fall apart crawling on a trail rather than doing 70 mph down the freeway...

-Mac

Can't say I blame you!

 

[shumthisway]

had an exhaust shop installed a new cat back and give an attempt on fixing the leak... they used washers, lock washers and a 2 nuts... still loosened. About to try Stage 8 Fasteners more specifically, part number 8950A (or B gotta measure how long the bolts in it right now are). If these don't work I'm about to the point where I'm going to have someone weld the bolts in place...