DEF light is on

Paul Owner/Technician New Jersey Posted   Latest   Edited  
2014 Chevrolet Silverado 3500 HD LT 6.6L (8 LML) 6-spd (6L90) — 1GC3KZC86EF139597
P22A0 — NOx Sensor Circuit Low Bank 1 Sensor 2
P22A1 — NOx Sensor Circuit High Bank 1 Sensor 2
P20EE — SCR NOx Catalyst Efficiency Below Threshold Bank 1
Def Light Is On
P16a8 - Glow Plug Control Module Temp-Intake Air Heater Temp Correlation
P11dc- Nox Sensor 2 Current Performance

Hi guys need help with see if someone shine some light I am lost on this truck. Looked at freeze frame data for code P22A0-nox 2 was at neg 100ppm and P11DC nox 2 was at 2650 ppm. 46 Grams of soot​.​ We did regen. Soot level down to 3 grams. Run the RFQT it failed​.​ So knowing we has NOx sensor code, We replaced both NOx sensors and reset the adaptations. Road tested for 25 minute highway came back did the regen and RFQT same thing failed again but no codes​.​ Follow the procedure from PIP 5007f​. ​ECM is up to date​.​ 

Tested the DEF 33.5%. Did metering quality test​.​ Good spray pattern and amount. Total regen and RFQT would be 5 same process​.​ Drove the vehicle 25 miles when cold​.​ Perform regen​. ​EGT 2, 3 and 4 around 1100 degree +- 20 EGT2 is the hottest 1120 degree. After few minutes of running. power down the vehicle for 2 to 4 min​.​ Did RFQT​.​ When doing RFQT NOx 1 is around 92 to 98 ppm and NOx 2 27 to 40 ppm​.​ Right after RFQT done at idle reads NOx 1170 and NOx 210ppm when road tested at cruise speed NOx 1 and 2 sometimes are pretty far apart sometime almost match and at idle is about same thing. Air Leak Equivalency Ratio when doing the RFQT is at 0.92:1. When command EGR 0% is at 1.07:1 and when EGR command 50% its at 0.39:1.

I'm at lost at this point. I don't want to put SCR converter before I'm sure I'm not missing anything.

Andrew Technician

Ok... there are few things that need to be done first. First... is the RFQT failing or timing out? After both NOX sensors are warmed up and reporting correctly, when you do a heavy accel and then decel with foot completely off of the accelerator pedal do both NOX1 and 2 drop below 10ppm? The other thing you can try is, run a regen, let truck sit off for about 20 mins then do the RFQT I have had

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Raul Owner/Technician

There are kits for cleaning the converter, I believe liquid moly sells. Have used twice with great result. Soot content needs to be lower.

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