Nissan Altima 2007-2012 Service Manual: P0420 three way catalyst function

DTC Logic

DTC DETECTION LOGIC

The ECM monitors the switching frequency ratio of air fuel ratio (A/F) sensor 1 and heated oxygen sensor 2.

A three way catalyst (manifold) with high oxygen storage capacity will indicate a low switching frequency of heated oxygen sensor 2.

As oxygen storage capacity decreases, the heated oxygen sensor 2 switching frequency will increase.

When the frequency ratio of A/F sensor 1 and heated oxygen sensor 2 approaches a specified limit value, the three way catalyst (manifold) malfunction is diagnosed.


DTC CONFIRMATION PROCEDURE


DTC CONFIRMATION PROCEDURE

1.PRECONDITIONING

If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at least 10 seconds before conducting the next test.

TESTING CONDITION: Do not hold engine speed for more than the specified minutes below.

>> GO TO 2.

2.PERFORM DTC CONFIRMATION PROCEDURE-I

CAUTION: Always drive vehicle in safe manner according to traffic conditions and obey all traffic laws.

1. Start engine and warm it up to the normal operating temperature.


1. Start engine and warm it up to the normal operating temperature.

2. Repeat the following procedure 3 times.

- Drive vehicle at a speed of 80 km/h (50 MPH) or more for at least 3 consecutive minutes.

NOTE: Keep the vehicle speed as steady as possible during the cruising.

- Stop vehicle with engine running.

NOTE: Never turn ignition switch OFF.

3. Select

    P0340 CMP sensor (phase)
    Description The camshaft position sensor (PHASE) senses the retraction of camshaft (INT) to identify a particular cylinder. The camshaft position sensor (PHASE) senses the piston position. When ...

    P0441 evap control system
    DTC Logic DTC DETECTION LOGIC NOTE: If DTC P0441 is displayed with other DTC such as P2122, P2123, P2127, P2128 or P2138, first perform trouble diagnosis for other DTC. In this evaporative em ...

    Other materials:

    B2556 push-button ignition switch
    Description The switch that changes the power supply position. BCM maintains the power supply position status. BCM changes the power supply position with the operation of the push-button ignition switch. DTC Logic DTC DETECTION LOGIC DTC CONFIRMATION PROCEDURE 1.PERFORM DTC CONFIRMATION ...

    Basic inspection
    COMPONENT INSPECTION Inspection AFTER A COLLISION WARNING: Inspect all seat belt assemblies including retractors and attaching hardware after any collision. NISSAN/INFINITI recommends that all seat belt assemblies in use during a collision be replaced unless the collision was minor and t ...

    B2619 BCM
    Description BCM requests IPDM E/R to supply power to steering lock unit. After receiving the power, the steering lock unit transmits an ON signal to BCM. DTC Logic DTC DETECTION LOGIC DTC CONFIRMATION PROCEDURE 1.PERFORM DTC CONFIRMATION PROCEDURE 1. Press the push-button ignition switc ...