Overall Function Check (Using GST)

Use this procedure to check the overall function of the 3-way catalyst 1. During this check, a DTC might not be confirmed.

1. Turn ignition switch to OFF position and wait 10 seconds.
2. Start engine and keep the engine speed between 3000-4000 RPM for at least one minute with no load.
3. Let engine idle for one minute.
4. Open hood.
5. Set voltmeter probes between ECM terminals No. 35 (HO2S1 bank 1 signal), No. 16 (HO2S1 bank 2 signal) and engine ground, and between ECM terminals No. 74 (HO2S1 bank 1 signal), No. 55 (HO2S2 bank 2 signal) and engine ground. See Fig 1 and Fig 2 .
6. Keep engine speed at a constant 2000 RPM under no load.
NOTE: If the voltage at terminal No. 35 or No. 16 does not switch periodically more than 5 times within 10 seconds at this step, perform trouble diagnosis for DTC P0133 or P0153 first. See DTC P0133 & DTC P0153 .
7. Ensure that the voltage switching frequency (high and low) between ECM terminals No. 74 and engine ground, or No. 55 and engine ground is less than that of ECM terminals No. 35 and engine ground, or No. 16 and engine ground. See Fig 1 and Fig 2 .
   • 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 specified, it means 3-way catalyst 1 does not operate properly. Go to DIAGNOSTIC PROCEDURE .

Fig 1: Testing HO2S Voltage Switching Frequency At ECM Terminals No. 16 & 35

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

Fig 2: Testing HO2S Voltage Switching Frequency At ECM Terminals No. 55 & 74

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