Guys please help

Inlet NOx sensor is acting up.

 

Reviewing the troubleshooting manual for EPA10 & GHG14 DD15 engines I found this
.
SPN 3216/ FMI 3 fault is SCR Inlet NOx sensor failed high. Code sets when there is short to power on NOx inlet circuit from the sensor to CPU.
Diagnosis is very short.
1. Disconnect the SCR Inlet NOx Sensor. 2. Inspect the Inlet NOx sensor and harness side connector for bent, spread or corroded pins. Is damage found? Repair it.
3. No damage. Replace the SCR Inlet NOx sensor.


SPN 3216/ FMI 18 fault is NOx Sensor Plausiblity Check.
Diagnosis is 35 steps. but 1st step after connecting Diagnostic link is to fix other faults first. So fix 3216-3 first.

SPN3223/FMI 7 fault is NOx Inlet Sensor Failure to activate.
This also says to fix other faults first. Then it goes on to similar steps of 3216-3.
2. Disconnect the SCR Inlet NOx sensor harness connector.
3. Inspect for signs of damage, bent, spread, corroded or unseated (pushed out) pins, signs of moisture in the connector or wire damage near the connector. Are any signs of damage present? Yes, then repair damage.
4. No, damage replace the SCR Inlet NOx sensor.

If you need to save the sensor wiring for a core then a socket like OTC 6931 oxygen sensor socket works well for removing NOx sensor. I have tried with weaker sockets and they seems to flex.

 

Thank you for posting back to the forum with your results. Great to hear you got the Inlet NOx sensor installed & your three related faults went away. I am curious what was cost of sensor and what was the core value around $200, perhaps?
The SPN4374/FMI 0 -This codes sets when the Diesel Exhaust Fluid (DEF) pump speed is higher that normal for a given DEF Pressure.
Possible causes:
Restriction in the DEF line between DEF tank and the DEF pump.
Restriction in the DEF line between DEF pump and the Dosing unit
Air the DEF line between the DEF tank and the DEF pump.
Restriction in the DEF pump
Failed DEF Pump.
Reading trouble shooting you want to do a good inspection of lines. Proper diagnosis may require Diagnosticlink , but I will post the troubleshooting steps.

 

Do I need to clear the codes with a code reader? Or will they go away?

 

So i need help trying to figure this out , I replaced a NOx sensor on my 2016 cascadia Freightliner and had a mechanic clear the codes after driving it for about 30 mins the codes came back on any ideas what's going on?

 

What codes did you have before changing NOx sensor and what codes do you have now. Was it the inlet or outlet NOx sensor? What is the last six digits of your VIN?