Overall Function Check

Use this procedure to check the overall function of the three way catalyst (Manifold). During this check, a 1st trip DTC might not be confirmed.

WITH GST 

1. Start engine and warm it up to the normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Start engine and keep the engine speed between 3, 500 and 4, 00 rpm for at least 1 minute under no load.
4. Let engine idle for 1 minute.
5. Open engine hood.
6. Set voltmeters probes between ECM terminal 35 (HO2S1 signal) and ground, and ECM terminal 74 (HO2S2 signal) and ground.
   Fig 1: Checking Voltmeter Probes Between ECM Terminal 35 And Ground

   Courtesy of NISSAN MOTOR CO., U.S.A.
7. Keep engine speed at 2, 000 rpm constant under no load.
8. Make sure that the voltage switching frequency (high & low) between ECM terminal 74 and ground is very less than that of ECM terminal 35 and ground.
   Fig 2: Checking Voltmeter Probes Between ECM Terminal 74 And Ground

   Courtesy of NISSAN MOTOR CO., U.S.A.

   Switching frequency ratio = A/B 

   A: Heated oxygen sensor 2 voltage switching frequency 

   B: Heated oxygen sensor 1 voltage switching frequency 

   This ratio should be less than 0.75. 

   If the ratio is greater than above, it means three way catalyst does not operate properly. Go to "DIAGNOSTIC PROCEDURE ".

   NOTE: If the voltage at terminal 35 does not switch periodically more than 5 times within 10 seconds at step 8, perform trouble diagnosis for DTC P0133 first. (See DTC P0133 HO2S1 .)