Nissan Micra K11 silhouetteK11

DTC P0420 THREE WAY CATALYST FUNCTION - On Board Diagnosis Logic / DTC Confirmation Procedure

EF & EC-7187prose procedure
CG10, CGA3

On Board Diagnosis Logic

The ECM monitors the switching frequency ratio of heated oxygen sensors 1 (front) and 2 (rear).
A three way catalyst with high oxygen storage capacity will indicate a low switching frequency of heated oxygen sensor 2 (rear). As oxygen storage capacity decreases, the heated oxygen sensor 2 (rear) switching frequency will increase.
When the frequency ratio of heated oxygen sensors 1 (front) and 2 (rear) approaches a specified limit value, the three way catalyst malfunction is diagnosed.

On Board Diagnosis Logic

P0420
Malfunction is detected when ...• Three way catalyst does not operate properly. • Three way catalyst does not have enough oxygen storage capacity.
Check Items (Possible Cause)• Three way catalyst • Exhaust tube • Intake air leaks • Injectors • Injector leaks • Spark plug • Improper ignition timing

DTC Confirmation Procedure

With CONSULT-II

DTC Confirmation with CONSULT-II

  1. 1
    Start engine and warm it up to normal operating temperature.
  2. 2
    Turn ignition switch off and wait at least 1 second.
  3. 3
    Turn ignition switch "ON" and select "DATA MONITOR" mode with CONSULT-II.
    CONSULT-II DATA MONITOR screen showing MONITOR NO DTC, ENG SPEED XXX rpm
    SEF058Y
  4. 4
    Restart engine and let it idle for at least 5 minutes.
  5. 5
    Drive vehicle in the following conditions at least 1 minute.
  6. 6
    If the first trip DTC is detected, go to "DIAGNOSTIC PROCEDURE", EC-7190.
  7. 7
    Select "SRT STATUS" in "DTC CONFIRMATION" mode with CONSULT-II.
    CONSULT-II SRT STATUS screen showing CATALYST CMPLT, HO2S HTR CMPLT, HO2S INCMP
    SEF648Z
  8. 8
    Verify that "CATALYST" is "CMPLT". If not "CMPLT", retry from the step 2).

Drive Conditions

ENG SPEED
ValueM/T: 1.0L 2,200 - 3,500 rpm; 1.3L 1,900 - 3,100 rpm; CVT: 1.0L 1,800 - 2,900 rpm; 1.3L 1,600 - 2,500 rpm
VEHICLE SPEED
Value70km/h - 100km/h
GEAR POSITION
ValueM/T: 5th; CVT: "D" position

GST with GST

DTC Confirmation with GST

  1. 1
    Start engine and warm it up to normal operating temperature.
  2. 2
    Turn ignition switch off and wait at least 1 second.
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See also

EC-7190

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