5.3l silverado misterious DTC

[Larsson]

Hi guys, my 5.3L silverado has a strange dtc code which keeps on popping up. I can read the dtc with the hp tuners OBD2 scanner/reader but I can't figure out what the code means.

 

I can delete the check engine light message but after a few hours it comes back on so there is something going on according the computer. The problem is I can't figure out what is going on.

 

Does anyone has an idea?

 

I took some pictures from my laptop of what's wrong according to hp tuners.

[rav3]

https://youtu.be/je2n6yczsfo?si=VeX57vH_pdx5p-i1

[CamGTP]

Do you have long tube headers?

[Larsson]

22 hours ago, rav3 said:

https://youtu.be/je2n6yczsfo?si=VeX57vH_pdx5p-i1

Thanks for the reply.

According the YouTube clip it is a problem with the cat. Is it a problem that relates to a lot of short trips with the truck?

 

I have the oem headers installed.

[CamGTP]

What are the actual fuel trims like if you data log them?

 

Are they very negative all the time or floating within that 5% of zero?

 

If it was me and the trims looks fine, I'd just disable the codes forever lol.

[Larsson]

I'm going to look at the fueltrims this weekend, if I have the time to do so. I'll give you an update as soon as possible.

 

Is it a good idea to pour some cat cleaner in the gastank? Just to see if it helps?

[Larsson]

Does this help to pinpoint the problem?

[newdude]

Original oxygen sensors in there still?  If any have been replaced, were they replaced with aftermarket ones?  

[Larsson]

Never changed the oxygen sensors. Maybe start there? Do I have to change all 4 of them? The ones before and after the cat? And only use gm genuine

[rlcole321]

What I notice as strange, is both downstream O2's are the same down to the 8th decimal point!!, got to be something going on there.

[Larsson]

18 hours ago, rlcole321 said:

What I notice as strange, is both downstream O2's are the same down to the 8th decimal point!!, got to be something going on there.

 

I looked back to the photo I shared and noticed it too. Maybe there is a short in the wirering somewhere?

[Larsson]

I'm going to look at the problem this saturday. If the weather stays dry.

Let you guys know what I found. In the mean time tips are more than welcome.

[Larsson]

I finished work early today so I had some time to check the connectors and wires of the O2 sensors. Everything looks normal. No damaged connectors or wires so far I can see. So I don't know how both the downstream sensors put out the same voltages. Maybe it's an idea just to replace all 4 O2 sensors and see where this leads to? 

[asilverblazer]

I don't think new sensors are going to fix that problem, I'd try to follow the sensor wiring to where they converge in the main harness then carefully examine from there upstream to the computer. 

 

The only way those two sensors are going to report identical voltage like that is if they are literally connected (via some problem) together somewhere. 

 

Unless someone else has some creative reasons why the PCM would see and report identical sensor voltages.

[Larsson]

I did some highway driving last week. About 400miles and the check engine light didn't came on since the last time I cleared the dtc's. Maybe the O2 sensors where a bit dirty? 

 

My plan now is to change all 4 O2 sensors and check the wiring from the two sensors past the cat. I keep you guys posted about the outcome.

 

In the mean time every suggestion/help is welcome