Aftertreatment SCR Performance Test: Test

WARNING: This page is about a different car, the 2018 Nissan Titan XD. However, it is still accessible from the selected car via links, so may be relevant.

WARNING: Exhaust system components can become hot enough during operation and testing to cause burns or ignite and melt combustible materials. The exhaust and exhaust components can remain hot after the vehicle stops moving and has been shut down. To avoid the risk of fire, property damage, burns or other serious personal injury, allow the exhaust system to cool before beginning repairs or service. Make sure that no combustible materials are located where they are likely to come in contact with hot exhaust or exhaust components.

Before performing an SCR Performance Test, follow the steps listed below:

Select an appropriate location to park the vehicle.
- On a surface that will not burn or melt under high temperatures (such as clean concrete or gravel, not grass or asphalt).
- Away from anything that can burn, melt, or explode.
  - Nothing within 0.6 m (2 ft) of the exhaust outlet.
  - Nothing that can burn, melt, or explode within 1.5 m (5 ft) (such as gasoline, wood, paper, plastics, fabric, compressed gas containers, and hydraulic lines).
Park the vehicle securely.
- Set the parking brake.
- Place the transmission in P (Park).
- Set the wheel chocks at the front and rear of at least one tire.
Set up a safe exhaust area.
- If bystanders can possibly enter the area, use barriers to keep people at least 1.5 m (5 ft) from the exhaust outlet during the SCR Performance Test.
- When indoors, attach an exhaust discharge pipe rated for at least 800°C (1500°F).
- Keep a fire extinguisher nearby.
Check exhaust system surfaces.
- Confirm that nothing is on or near the exhaust system surfaces (such as tools, rags, grease, or debris).
Prepare for engine speed changes during the SCR Performance Test.
- Stay clear of the engine compartment.
Begin the SCR Performance Test.
- CONSULT must be used to perform the SCR Performance Test.
- The engine will create enough heat to run the test. Engine speed will increase and the turbocharger can whistle loudly during the testing process. Once the test is complete, the engine will automatically return to normal idle speed.
Monitor the area.
- Make sure that the vehicle and surrounding area is monitored during the SCR Performance Test. If any unsafe condition occurs, shut the engine OFF immediately.

To stop the test, engage the brake, or throttle pedal; or turn the engine OFF.

Once the test is complete, exhaust gas and exhaust surface temperatures will remain elevated for 3 to 5 minutes.

Before starting the SCR Performance Test, inspect the exhaust piping for leaks, cracks, and loose connections.
Tighten the exhaust clamps, if necessary. Inspect the exhaust and system for leaks. Tighten clamps as necessary. Refer to the appropriate procedure or equipment manufacturer service information for torque specifications. Any leaks in the exhaust system will cause the SCR Performance Test to be less efficient. This will result in the test running longer and possibly not completing.
The test can be found under the ECM Diagnostics Test menu in CONSULT. Follow the on-screen instructions to perform the test.
To stop the SCR Performance Test at any time during the test:
- Select the STOP button on the CONSULT monitor screen.
- Depress the brake.
- Depress the accelerator pedal.
- Turn the engine off.
The SCR Performance Test will perform the following actions:
Clean the after treatment system of any diesel exhaust fluid deposits.

Courtesy of NISSAN NORTH AMERICA, INC.
- Cleaning the after treatment system of diesel exhaust fluid deposits can take up to 2 hours to complete. If deposits are detected after 2 hours of run time, the test will time out.
Perform a NOx sensor rationality test.
- The intake NOx sensor (1) and outlet NOx sensor (2) readings will be compared to determine if they are working properly.
- If one, or both, of the NOx sensors fail the rationality test, the test will stop and a pop-up message will be displayed, stating that the NOx sensor has failed and troubleshooting is required.
Check the SCR catalyst efficiency.
- Diesel exhaust fluid will be injected into the after treatment system and the outlet NOx sensor reading will be compared to the intake NOx sensor reading to determine the efficiency of the SCR catalyst.
- If the SCR catalyst fails the efficiency test, a pop-up message will be displayed, stating that the SCR catalyst must replaced.
During the SCR Efficiency Test, the following will be monitored:

Courtesy of NISSAN NORTH AMERICA, INC.
- SCR inlet temperature (1).
- SCR outlet temperature (2).
- Intake NOx sensor reading (3).
- Outlet NOx sensor reading (4).
Once the SCR Performance Test is started, follow CONSULT on-screen instructions. When the test is started, the engine idle speed will be raised automatically to the required level.
- Through engine controls, the engine will operate in a manner to build exhaust heat. The turbocharger will emit a slight whining noise during this test. This is normal.
- Once the SCR Performance Test is complete, the engine will automatically return to normal idle speed.
Once the test is complete, check for active P-codes and/or engine indicator lamps. If any active P-codes are present, follow the appropriate P-code troubleshooting tree.