P0421 Warm Up Catalyst Efficiency Below Threshold (Bank 1)

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P0421 Warm Up Catalyst Efficiency Below Threshold (Bank 1)

Technical Description

Warm Up Catalyst Efficiency Below Threshold (Bank 1)

What does that mean?

This diagnostic trouble code (DTC) is a generic powertrain code, which means that it applies to OBD-II equipped vehicles. Although generic, the specific repair steps may vary depending on make/model.

Basically this means that the oxygen sensor downstream of the catalytic converter on bank 1 is detecting that the converter is not working as efficiently as it should be (according to specs). It is part of the vehicle emissions system.

Symptoms

Causes

A code P0421 may mean that one or more of the following has happened:

  • The catalytic converter is no longer functioning properly
  • An oxygen sensor is not reading (functioning) properly
  • A sparkplug is fouled up
  • Possible Solutions

    Measure the voltage at the oxygen sensor on Bank 1 (the rear sensor, or the sensor after the converter). In fact, it would be a good idea to test each oxygen O2 sensor while you’re at it.

    One thing to note is that many vehicle manufacturers offer a longer warranty on emissions-related parts. So if you have a newer car but it’s out of it’s bumper-to-bumper warranty, there still may be warranty on this type of problem. Many manufacturers give a five year, unlimited mileage warranty on these items. It’s worth checking into.

    Need help?

    Let us fix your problem. You are most welcome our diagnosis experts have in most cases the knowledge and skills to find the cause of the error code p0421 and to solve the problems.

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    "Delete Error Code Permanently, Disable DTC Error Code Function for p0421 in the ECU"

    In extreme cases, we even have the option to permanently remove the specific DTC p0421 and disable the function of the specific error code in the ECU. All other fault code functions will then continue to work to protect the engine. This is different from clearing an error code with a diagnostic device. We have the option to permanently remove the function of the specific error code, so that it never comes back. Also emergency running that occurs on the specific error code can be solved in most cases.

    Of course we prefer to first try to solve the cause of the error code, but sometimes the only solution is to permanently disable the DTC function of p0421.

    Make an appointment for permanent removal of p0421