No O2 Sensor Data, Cat or O2 Fix?

[annihil8ted]

Hello All!

I have a MIL light and when I scan it, I'm pulling up a P042 and P0432. Checking the threads, it looks like I'm having issues with either my O2 sensors (hopefully) or my CAT needs replacement.

I tried reading O2 data but I'm getting no data input on my reader. It's a OBDLink MX+ and I'm using the standard OBDLink app. This isn't exactly a no-name reader so I'm surprised that it can't pull data. Could I have some issues with my PCM?


It's 4.0 TJ and upon receiving it from the PO, I've noticed the exhaust is a lot louder than stock. There is an aftermarket exhaust on it but I'm wondering if maybe the CAT is gone. Sounds like Jake brakes in 3rd off throttle and I can get pops and bangs. If not the CAT, could it be the O2 sensors giving bad readings, causing the engine to run rich?

My oil temps are good but my coolant temp is a tick to the right of 210 if that's any indication of anything. I will also say that I do smell exhaust but unsure if it's a leak or because of age

 

[Sayantsi]

Could be a wire, a sensor, both sensors, and ultimately the cat. But, if you have no data stream from the O2 sensors, I'd start with the wires and sensors to make sure there is continuity and if the sensors are working properly. If you know what you're smelling from the exhaust, you'd know if you have a cat or not.

 

[annihil8ted]

Yeah that's the conclusion I'm leaning towards; most likely my cat has gone bad

The smell isn't bad, really only if I open the drivers window for some reason. Doesn't happen when both windows are open and not really if I'm just hanging around the vehicle

As far as sensors or wires going bad, would there be other warnings or codes? My reader is saying there is no data, not that the data is 0

 

[macleanflood]

I wouldn't replace anything until I could read live data from the PCM and check both O2 voltages and fuel trims.

You can use an IR thermometer to test your cat

-Mac

 

[annihil8ted]

You can use an IR thermometer to test your cat

I do have one on hand, what are some of the things I should be on the look for?


Would it be possible my PCM has gone bad?

 

[TJ Jim]

I do have one on hand, what are some of the things I should be on the look for?


Would it be possible my PCM has gone bad?

You are looking for a huge temp difference between incoming temp to out going temp at the cat. Hotter at the outgoing end.

 

[annihil8ted]

You are looking for a huge temp difference between incoming temp to out going temp at the cat. Hotter at the outgoing end.

Hmm i would have thought the other way around? So it should be before the cat and after the cat?

 

[TJ Jim]

The catalyst in the catalytic converter burns all the unburnt fuel which makes the output hotter.

 

[annihil8ted]

Hello all,

Finally am in a place to properly diagnose this. Since the last update I've figured out a few things.

Originally I thought the cats were modified however now I can confirm they're not. What was changed is the muffler and hence explains why it's so loud.

I think I am now pulling sensor data and here's a few example as follows:

B1S1 .76V
B1S2 .78V
B2S1 .78V
B2S2 .82V

B1S1 .28V
B1S2 .26V
B2S1 .1V
B2S2 .54V

B1S1 .14V
B1S2 .12V
B2S1 .66V
B2S2 .78V

The values do seem to jump quite a bit but I don't have experience here to say this is normal or not. My gut tells me it's not so it would be awesome if someone can help me confirm.

 

[annihil8ted]

I'll also add that there does seems to be a little bit of an exhaust smell in the cabin if I open the window while driving. With windows shut, there is nothing so I'm now also wondering if I'm dealing with a small exhaust leak? How would I check that?

 

[macleanflood]

Those look like good O2 numbers.

Seafoam is a good way to find exhaust leaks. With the engine running pull the vacuum line running to the brake booster and dip it in the can. Run the throttle to keep it running. Watch for smoke coming out of places it shouldn't.

-Mac