4 O2 sensor codes at once

Fortzen1305

Fortzen1305

Member
Joined
May 21, 2021
Messages
35
Location
Colorado
This weekend my 05 LJ with 105K mi threw P0031, P0037, P0051, P0057. I cleared the code and it came back the next day. I will probably go ahead and replace them anyway because they’re all original and likely need replaced.

I’m looking for help on what to be thinking about such as:

1. Is this a bad PCM?
2. Blocked cat?
3. Just bad sensors?

Any ideas on where to start with all this?
 
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All of those codes are for O2 heater low voltage, and it's incredibly unlikely that somehow all four of your O2 sensors failed in the exact same way at the exact same time. It's also definitely not a bad or blocked cat.

It's far more likely that this is a wiring or PCM issue. Unplug whichever O2 you can get at most readily and check the heater pins for proper 12V and ground - with a test light as well so that you can verify that the circuit is actually capable of carrying current.
 
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Ya, seems like a ground issue to me. I'd check at the battery cables for fun and go from there. There's an important ground on the block and firewall as well. The cables should look perfect.
 
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I got the same codes all at once on my '06. The codes had no effect on drivability. I tried the reset. I checked, cleaned and tightened grounds. I replaced all four O2 sensors. The codes kept returning. I was fortunate enough to have the issue diagnosed by a retired CDJ mechanic and electrical guru. It was a failed PCM. I was able to source an NOS MOPAR PCM and have him program it. The codes haven't returned in three years.
 
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Wranglerfix said:
Automatic pcm failures Include:

All o2 sensors showing bad when good, high transmission temperatures, hard shift from 1st to 2nd when cold and 1600 codes (processor failure on the ECM side.)

@Fortzen1305 You can call me to discuss in further detail at 866-888-7710.
Click to expand...

I will shoot you a call tomorrow (Monday) and get this figured out. It definitely has the hard shift issue and I’ve been tracking the PCM issue with this year Jeep. Thanks for reaching out @Wranglerfix.
 
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Jerry Bransford said:
Very likely a bad PCM. Call Mark at Www.wranglerfix.com who can verify if that's the problem. @Wranglerfix
Click to expand...

Fortzen1305 said:
This weekend my 05 LJ with 105K mi threw P0031, P0037, P0051, P0057. I cleared the code and it came back the next day. I will probably go ahead and replace them anyway because they’re all original and likely need replaced.

I’m looking for help on what to be thinking about such as:

1. Is this a bad PCM?
2. Blocked cat?
3. Just bad sensors?

Any ideas on where to start with all this?
Click to expand...

I had all four codes on my LJ and tried the PCM swap, manual tranny though which has different PCM issues than the automatic. Mine was a bad cat, and that can easily be confirmed by removing the exhaust and looking.

Before dropping a bunch of money on a PCM or parts, you can check this for free in your driveway.

IMG_20220424_163644.jpg


IMG_20220424_163413.jpg


IMG_20220424_163407.jpg
 
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skrelnik said:
I had all four codes on my LJ and tried the PCM swap, manual tranny though which has different PCM issues than the automatic. Mine was a bad cat, and that can easily be confirmed by removing the exhaust and looking.

Before dropping a bunch of money on a PCM or parts, you can check this for free in your driveway.

View attachment 335044

View attachment 335045

View attachment 335046
Click to expand...

I read through your entire post and saw that. I'm going to check the cats this week. I do think it's PCM related because I have the hard shift issue and at idle it'll sometimes it'll drop really low and then come back up.
 
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