To clear the fault code, ambient air temperatures must be greater than 0°C (32°F).

1. Connect DiagnosticLink^® .
2. Using refractometer from DEF Test Kit W060589001900, measure DEF percentage. Is DEF percentage between 28 and 36%?
   1. Yes; go to step 3.
   2. No; refer to appropriate manual for DEF tank cleaning/flushing procedure, then Go to step 12.
3. Turn ignition ON (key ON, engine OFF).
4. Compare DEF pressure to ambient air pressure (baro) and DEF air pressure. Is DEF pressure within 29.6 kPa (4.3 psi) of ambient air pressure (baro) and DEF air pressure?
   1. Yes; go to step 5.
   2. No; replace the DEF pressure sensor. Go to step 12.
5. Visually check all DEF supply and air lines for physical damage (kinks, cracks, leaks, disconnects). Is any damage found?
   1. Yes; repair as necessary; Go to step 12.
   2. No; go to step 6.
6. Perform a DEF quantity test service routine and record the amount of DEF fluid level dispensed. Is the dispensed DEF fluid level between 108 and 132 mL (3.65 and 4.46 oz)?
   1. Yes; go to step 12.
   2. No; go to step 7.
7. Remove DEF air pressure and temperature sensors.
8. Remove the DEF inlet delivery line and DEF air supply line from metering unit.
9. Remove DEF nozzle from the Aftertreatment Device (ATD) box.
10. Flush warm water into DEF air pressure and temperature sensor cavities in the DEF metering unit until water flows from the DEF inlet and DEF nozzle. Reinstall sensors and perform the DEF quantity test service routine. Is the dispensed DEF fluid level between 102 and 138 mL (3.45 to 4.66 oz)?
    1. Yes; Go to step 12.
    2. No; repeat flushing procedure. Go to step 11.
11. Perform a DEF quantity test service routine and record the amount of DEF fluid level dispensed. Is the dispensed DEF fluid level between 102 and 138mL (3.45 to 4.66 oz)?
    1. Yes; Go to step 12.
    2. No; replace DEF Metering Unit. Go to step 12.
12. Connect DiagnosticLink^® . Monitor (chart) the following parameters:

• ASL102 Engine Speed
• AS018 Selective Catalyst Reduction (SCR) Inlet Temperature
• AS019 SCR Outlet Temperature
• AS035 SCR Inlet NOx Sensor
• AS036 SCR Outlet NOx Sensor
• AS101 NOx Conversion Efficiency
1. Start engine and perform a parked regeneration. Retain the log file. Does the NOx conversion efficiency rise and stay above 70% (0.70) during the regeneration?

1. Yes; clear faults and Go to step 17.
2. No; Go to step 14.
1. Disconnect the DEF doser electrical connector.

NOTE: Disregard SPN 3361/FMI 5 which will set with valve unplugged.

1. Turn the ignition ON (key ON, engine OFF).
2. Perform a low temperature Aftertreatment Device (ATD) check using DiagnosticLink to check for a drifted temperature sensor. Are the inlet NOx sensor and outlet NOx sensor readings within 50 Parts Per Million (PPM) of each other?
   1. Yes, Go to step 17.
   2. No, replace the SCR inlet NOx sensor. Go to step 18.
3. Start the engine and perform a complete parked regeneration. The regen will burn off any DEF deposits in the aftertreatment. Verify repairs.
4. Perform a low temperature Aftertreatment Device (ATD) check using DiagnosticLink to check for a drifted temperature sensor. Are the inlet NOx sensor and outlet NOx sensor readings within 50 Parts Per Million (PPM) of each other?
   1. Yes, clear faults and release vehicle.
   2. No, replace the SCR outlet NOx sensor. Verify repairs.