One of the most common fault codes occurring in EPA10/GHG14 model units. This fault code appears when the ACM reads that NOx conversion is lower then spec. Based off the SCR inlet & outlet NOx sensors.
Conditions in which the code will appear:
- During regen the DEF doser begins dosing
- 1000-1500 rpm @15-100% load
- SCR inlet temp less then 650C/ambient temp greater than 0C/coolant temp greater than 70C
This code will put the unit in a derate for at least one drive cycle but will not shut down the unit.
How to troubleshoot
- Verify no other emission related components were recently repaired. Perform a regen to verify code.
- Verify for any air system related fault codes, if any repair those first.
- Verify for any EGR related faults, if any repair those first.
- Verify for any DEF related faults, if any repair those first.
- Verify for any NOx sensor, DPF/DOC/SCR temp or pressure sensor fault. If any repair those first.
- Check DEF quality, verify there is no contamination. Use P/N DDE W060589001900 for more accurate readings. Replace DEF and flush system if any damage/contamination is present, then regen to verify repair.
- Using DDDL compare DEF pressure sensor to barometric pressure sensor reading. Make sure they are within 4.3PSI, if not replace DEF pressure sensor.
- Using DDDL perform DEF quantity test. Remove the DEF doser injector and verify the quantity of DEF fluid being sprayed. Spec is between 100-135ml. If not replace and regen to verify repair.
- Disconnect DEF doser injector connector and perform a Low temp regen using DDDL. Monitor inlet & outlet NOx sensor readings(PPM) make sure they are within 50ppm, if not replace the sensor with most inaccurate/erratic reading.
- After all basic checks have been performed. Regen the unit and monitor NOx efficiency and release unit if unit has over 70% efficiency.
- If unit does not pass a regen perform another regen and monitor SCR inlet & outlet temp sensors.
- If the inlet SCR temp sensor reads 38C lower than the SCR outlet temp sensor, replace the One box and check for up stream failure
- If temp sensors are within 38C, perform another low Temp regen. Monitor DPF/SCR temp sensors and replace sensors that have an erratic movement during the regen process.