P0420 NISSAN - Catalyst System Efficiency Below Threshold Bank 1

Repair Importance Level: 2/3
Repair Difficulty Level: 2/3

P0420 NISSAN Causes

  • Faulty Three-way Catalyst Converter Bank 1
  • Exhaust Tube
  • Intake Air Leaks
  • Faulty Oxygen (O2) Sensor
  • Faulty Fuel injector(s)
  • Leaking Fuel Injector (s)
  • Faulty Spark plugs
  • Improper Ignition Timing
  • Faulty Engine Control Module (ECM)
  • Dirty Air Filter
  • P0420 NISSAN Notes

    As the code description implies the P0420 code means that the vehicle's control module has detected that the three-way catalytic converter is not working properly (is not as efficient as the factory is expecting). Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases the catalytic convert needs to be replaced to fix the problem. If the P0420 code is combined with other codes, try fixing the other codes first.

    Very common problem with Nissan vehicles. There are Nissan factory service bulletins for the following Nissan models:

    2000 Nissan Maxima
    2001 Nissan Maxima
    2000-2001 Nissan Maxima Factory Service Bulletin OBDII Code P0420

    2001 Nissan Frontier
    2001 Nissan Xterra
    2001 Nissan Frontier-Xterra Factory Service Bulletin OBDII Code P0420

    2004 Nissan Altima
    2005 Nissan Altima
    2004-2005 Nissan Altima Factory Service Bulletin OBDII Code P0420

    2004 Nissan Altima
    2005 Nissan Altima
    2006 Nissan Altima
    2004-2006 Nissan Altima Factory Service Bulletin OBDII Code P0420

    2005 Nissan Frontier
    2006 Nissan Frontier
    2005-2006 Nissan Frontier Factory Service Bulletin OBDII Code P0420

    First diagnose P0420 NISSAN code

      Check the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded terminals.

    Cost of diagnosing the P0420 NISSAN code

      Labor: 1.0

      The cost of diagnosing the P0420 NISSAN code is 1.0 hour of labor. The auto repair labor rates vary widely across the country, and even within the same city. Most auto repairs shops charge between $75 and $150 per hour.

    P0420 NISSAN Symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)
  • P0420 NISSAN More Information

    Need more information on how to fix the P0420 NISSAN code?
    Get Access to Factory Service Manuals

    P0420 NISSAN Description

    The Engine Control Module (ECM) monitors the switching frequency ratio of heated oxygen sensors 1 (front O2 sensor) and heated oxygen sensors 2 (rear O2 sensor).

    A three way catalyst converter (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 heated oxygen sensors 1 and 2 approaches a specified limit value, the three way catalyst malfunction is diagnosed.