2016 Peterbilt 579 ISX15 fault clodes 3232 & 3714 (2024)

579 2016
Left truck running over night (was -30f), started driving in morning and started getting Engine derate in 1 hr, Power reduced due to SCR, and SCR fault detected or altered.
Did a 1 hour manual regen, but codes kept showing.
Had to do a load and all throughout the day I kept getting those codes, with the derate in 59minutes reseting as I was driving.
Noticed loss of power as well going up hill.

Anyway had a local mechanic plug it in and I got 2 codes. He tried doing a regen but the doser valve wasnt turning to Active, so was useless to do 1. He also said my soot level was normal.

2 codes:
Fault code 3232
Description: Aftertreatment 1 Intake NOx sensor - Abnormal update rate

Fault code 3714
Description: Engine Protection Torque Derate - Condition exists

So what can I do here? He recommended that I take it to Cummins and have the DPF cleaned as well as replace both intake and outlet NOx sensors.
Was thinking of cleaning dpf either way, its been around 175k since last cleaning

Dpf has nothing to do with that fault. The intake and outlet NOX sensors are intelligent devices.

The derate is due to the nox sensor f/c. Any aftertreatmemt related f/c will cause a derate in these engines. That fault is an information only fault code and will clear as soon as the 3232 goes inactive.

I mistook this f/c at first glance for another one and gave out some inaccurate advice. There is a range of data link and power checks needed before replacement. My apologies.

Abnormal update rate means that your ECM is not able to communicate with the device in question. You could have a wiring issues to the sensor. Stop guessing and changing parts and take it in for professional diagnosis.

I also forgot to mention that a day before the fault codes popped up I couldn’t turn the turn the truck on cause of the cold, gave it a few tries but nothing. had the voltage but low amps, was able to turn the truck on after charging, but maybe that has some play? (codes didnt pop up till next day though once I started driving and idling it all night though)
Battery not giving enough power or a bad fuse/relay, not sure. Did take it to a local shop so we’ll see tomorrow

So Peterbilt dealer couldnt fix the issue. Still have a check engine light, engine will derate in 4 hours, scr system detected or altered and the red light is solid on the def gauge.

They did find a bad intake NOx connector which they said might be the issue
Will change it tomorrow and see if that does it.

Would draining my DEF tank and putting in fresh DEF maybe help?
It was below 0 last 2-3weeks and entire time I had a full tank, so maybe the quality of the DEF deteriorated? (havent drove at all during that time)

Still have 3232 coming back?

Yeah only that 1 and the 3714. The connector did look a little broke when my local mechanic changed the NOx sensor but he had to push it super hard to get it to click and plug in fully.

now will changing that connector fix and clear the code? idk maybe, i hope, running out of ideas.

You may have an outlet nox sensor on the inlet. The connectors have blind keys, but can be forced on and come apart hard as you describe. The connector and sensor must match grey to grey (inlet) and black to black (outlet).

I would replace the inlet NOx with a new from dealer or Cummins.

If the fault persists and is still intermittent , my money still on wiring issue.

“There are active codes 3714 22xs, 3232 426xs, it is the NOx sensor code. Went to look at the 3232 code found that there is power at the inlet nox but it will not carry a load. Looked for break in the harness. Wiggling the harness and was able to get the lamp to light. The harness was removed at the 14 way connector and tested the wires from here to the nox sensor plug in. This is open found the wires back of the shell. The lock tab to the wires is broken. Got a new shell and transferred the wires and seals. This does not fail at this time. Tried to plug in the nox sensor back in and it was more difficult then removal of it. The connector end is broken.”
From the dealer

Theyre new inlet and outlet NOx sensors, installed them last week. Youre saying theres a chance theyve been installed
incorrectly? The inlet has foil and outlet doesnt? easy to tell which 1 is which