Circuit/System Testing

WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.

Ignition OFF. Test the reductant system for contamination. Refer to Contaminants-in-Diesel Exhaust Fluid Diagnosis .
- If any conditions are found
  Repair as necessary
- Go to next step: If no conditions are found
Ignition ON, command the Reductant System Priming and Leak Test Device Control.
Verify that the system is able to build up and reach the reductant pressure sensor parameter greater than 450 kPa.
- If less than the specified range
1. Command the Reductant Pump Duty Cycle Command Device Control to 50% with a scan tool.
2. Verify that the desired Reductant Pump Speed and actual Reductant Pump Speed parameters are equal.
  - If not equal
    Refer to DTC P105A
  - Go to next step: If equal
    Go to next step: Replace the emission reduction fluid supply pump module
- Go to next step: If within the specified range
Verify there are no leaks, kinks or restrictions in the reductant lines.
- If any condition is found
  Repair as necessary
- Go to next step: If no conditions are found
Verify the Emission Reduction Fluid Injector Quantity Test passes.
- If the test does not pass
  Repair as necessary
- Go to next step: If the test passes
Disconnect the Q61 Reductant Injector electrical connector.
NOx sensors at operating temperature and engine idling, verify NOx sensor 2 NOx concentration less than 50 ppm greater than NOx sensor 1 NOx Concentration.
- If NOx sensor 2 NOx Concentration is 50 ppm or more greater than NOx sensor 1 NOx Concentration
  Replace the B195B Nitrogen Oxides Sensor 2
- Go to next step: If NOx sensor 2 NOx Concentration is less than 50 ppm greater than NOx sensor 1 NOx Concentration
Idle engine at 1 500 RPM for 10 min and verify Exhaust Gas Temperature Sensor 2 is cooler than 150°C (302°F). If warmer than 150°C (302°F), verify Exhaust Gas Temperature Sensor 2 is warmer than 180°C (356°F) for 30 minutes.
Verify NOx sensor 1 NOx Concentration and NOx sensor 2 NOx Concentration are within 50 ppm of each other
- If not within the specified range
  Replace the B195A Nitrogen Oxides Sensor 1
- Go to next step: If within the specified range
Connect the Q61 Reductant Injector electrical connector.
Verify none of the conditions listed below exist:
- Leaking fuel injectors. Refer to Fuel Injector Balance Test .
- Engine oil consumption. Refer to Oil Consumption Diagnosis .
- Engine coolant consumption. Refer to Coolant in Combustion Chamber .
- An engine mechanical condition. Refer to Symptoms - Engine Mechanical .
- If any condition is found
  Repair as necessary
- Go to next step: If no condition is found
Replace Nitrogen Oxides Catalytic Converter.