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. Turn ignition switch OFF and wait at least 10 seconds.
2. Start engine and keep the engine speed between 3,500 and 4,000 RPM for at least 1 minute under no load.
3. Let engine idle for 1 minute.
4. Open engine hood.
5. Set voltmeters probes between ECM terminals 16 [HO2S1 (bank 1) signal], 35 [HO2S1 (bank 2) signal] and ground, and ECM terminals 55 [HO2S2 (bank 1) signal], 74 [HO2S2 (bank 2) signal] and ground.
6. Keep engine speed at 2,000 RPM constant under no load.
   Fig 1: Using DVOM To Test Overall Function (1 Of 2)

   Courtesy of NISSAN MOTOR CO., U.S.A.
NOTE: If the voltage at terminal 16 or 35 does not switch periodically more than 5 times within 10 seconds at step 7, perform trouble diagnosis for DTC P0133, P0153 first. See DTC P0133, P0153 HO2S1  .
Fig 2: Using DVOM To Test Overall Function (2 Of 2)
Courtesy of NISSAN MOTOR CO., U.S.A.
7. Make sure that the voltage switching frequency (high & low) between ECM terminals 55 and ground, or 74 and ground is very less than that of ECM terminals 16 and ground, or 35 and ground.

   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 (manifold) does not operate properly. Go to DIAGNOSTIC PROCEDURE