Different codes every time I clear it, for same issue(?)

[SlippytheDisco]

So long story short, august I replaced ALL 02 sensors. Went off-roading, front one (upstream) had issues, finally fixed it. 750 miles later, downstream starts popping about 3 codes.. I do the same thing as upstream (clean it and the catalytic converter itself, which cleared 2/3 codes, the one not being cleared which is p1159), then swap the two downstream to see if it is the cat or not. I thought it ended up being the 02 sensor, ordered a new one. Put the new one on today, 13 miles later, check engine light comes back on. I get it scanned and there’s like 6 different codes, mainly being about an exhaust manifold leak going off. For reference, the codes I was having before replacement were bank 2 sensor 1(or 2), having to do with the lambda controller (off the top of my head P1173), this was the only code before replacement today still going. I decide to put the “old” 02 sensor back on (less than 5k miles), drove it around for approximately 25 miles, check engine light comes back on. Get it scanned, and the only two codes popping up are P0159 and P1159. P1559 was there earlier today, but the exhaust manifold leak and the other 500 million codes going off were gone. I am so confused at this point, and have no clue what is ACTUALLY the issue bc there’s so many different codes going off randomly. Please help. Thank you.

 

[SlippytheDisco]

I’d also like to apologize for the long statement, just wanted to get as many details in as I could. Thanks, because I am fed up with 02 sensors at this point.

 

[kris812]

From my seat, it sure sounds like and exhaust leak on the manifolds, Y pipe flanges, or head gasket.

Any leaks are bad as O2 won't be seeing all the exhaust, and start tripping codes.

I highly recommend buying all ELM 327 and use torque app to SEE in live time what the O2 are doing. Upstreams should be oscillating or look like a wave, downstreams should be active but low voltage readings. If you're downstream is swinging like you're upstream, the cat's bad.

 

[kris812]

Also worth noting it's good practice that both upstreams should be changed at the same time. You don't want one bank running different than the other and slightly different O2 will make sure that happens.

 

[SlippytheDisco]

Also worth noting it's good practice that both upstreams should be changed at the same time. You don't want one bank running different than the other and slightly different O2 will make sure that happens.

Both upstreams were replaced at the same time, I was able to clean it and the code went away. This is a stupid question, but where/ how do I buy the ELM app? Also, what would cause one downstream 02 sensor to throw all of those exhaust manifold leaks, while another one only says p1159? Thank you for your help, I’m pretty lost. I’m going to check for a leaks in the exhaust manifold and other places u mentioned as well. Thank you.

 

[SlippytheDisco]

Also worth noting it's good practice that both upstreams should be changed at the same time. You don't want one bank running different than the other and slightly different O2 will make sure that happens.

U were right, significant bubbling where the Y pipe connects to the exhaust manifold, on both sides. The passenger side was really severe. I tightened all of the bolts, and while they seemed to be loose, the bubbling still continued afterwards. Is this a case of needing new gaskets, or could this be needing a new manifold/ y pipe entirely?

 

[Greg_M]

significant bubbling where the Y pipe connects to the exhaust manifold, on both sides. The passenger side was really severe. I tightened all of the bolts, and while they seemed to be loose, the bubbling still continued afterwards. Is this a case of needing new gaskets, or could this be needing a new manifold/ y pipe entirely?

The Y pipe to flange welds on my example were/are terrible to say the least. A cold, convex bead that all but missed the joint. While I had the manifolds off I used exhaust cement to patch it from the top filling the space between the pipe and flange. My replacement O2 sensors also leak. No codes though.

 

[SlippytheDisco]

The Y pipe to flange welds on my example were/are terrible to say the least. A cold, convex bead that all but missed the joint. While I had the manifolds off I used exhaust cement to patch it from the top filling the space between the pipe and flange. My replacement O2 sensors also leak. No codes though.
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Awesome, thanks for the help. So you think a leaking 02 sensor isn’t something to worry about?

 

[kris812]

Y pipe gaskets are cheap and fairly easy to change, as long as no studs break!!

I'd start there, but the good old shop vac on exhaust, on exhaust, with a bubble bath and you'll find all the tiny leaks.. But gaskets first..

ELM327 is a Bluetooth obd dongle device, eBay/Amazon. "torque pro" application on Android is what I use.. A good elm327 will even work with Roberts fuel reset app as well on D1s.

 

[rovercanus]

Did you mention brand of o-sensors? Some simply don't work.

 

[Greg_M]

Awesome, thanks for the help. So you think a leaking 02 sensor isn’t something to worry about?

I wouldn't say that, I'll change them out again some day. But for now there are no related codes and I have more pressing things to sort out first.

 

[SlippytheDisco]

Y pipe gaskets are cheap and fairly easy to change, as long as no studs break!!

I'd start there, but the good old shop vac on exhaust, on exhaust, with a bubble bath and you'll find all the tiny leaks.. But gaskets first..

ELM327 is a Bluetooth obd dongle device, eBay/Amazon. "torque pro" application on Android is what I use.. A good elm327 will even work with Roberts fuel reset app as well on D1s.

Thank you, I will look into that. It turns out it was leaking where the manifold meets the y pipe. I am in the process of replacing the gaskets. If I am unable to fix it before Monday, is this unsafe at all to drive as a commuter with the issue?

 

[SlippytheDisco]

Did you mention brand of o-sensors? Some simply don't work.

It was leaking out of the exhaust manifold connection to the Y pipe, got the gaskets changed and stripped a bolt in the process, which is quite the bummer. However, the one side that didn’t have a bolt stripped still leaks a bit of air, any suggestions as to why?

 

[rovercanus]

It was leaking out of the exhaust manifold connection to the Y pipe, got the gaskets changed and stripped a bolt in the process, which is quite the bummer. However, the one side that didn’t have a bolt stripped still leaks a bit of air, any suggestions as to why?

That I don't know. I've never tested o sensors themselves for leaks.
I use Bosch sensors because I know they work. I think others have used NKG sensors also.