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P0424 OBD-II Trouble Code: Heated Catalyst Temperature Below Threshold (Bank 1)

check engine light

P0424 code definition

When the P0424 code is stored, it indicates that the vehicle’s three-way catalytic converter is malfunctioning or is not working as efficiently as expected by the manufacturer’s standards. In this case, the problem is detected when oxygen storage capacity has decreased, increasing the catalytic converter’s switch rate, causing a malfunction that is then signaled to the PCM (powertrain control module), which stores the code and illuminates the Check Engine Light.

What the P0424 code means

The P0424 code warns that the catalytic converter is not functioning to its normal capacity. This can cause a number of problems for the vehicle, but most notably it could mean that the vehicle’s emissions will increase and the vehicle will not be able to pass an OBD-II emissions test required for registration in most states.

What causes the P0424 code?

There are three main causes that can result in a P0424 code being stored by the PCM. These include:

  • A defective catalytic converter
  • A faulty oxygen sensor
  • An air leak before the catalytic converter

While air leaks and faulty oxygen sensors do occur from time to time, in most cases the cause of the problem is a defective catalytic converter and replacing it is the best solution.

In rare cases, the P0424 could be stored due to a faulty PCM, but the other causes listed above are much more common.

What are the symptoms of the P0424 code?

In almost all cases, the only noticeable symptom of a P0424 code being stored is the illumination of the Check Engine light.

How does a mechanic diagnose the P0424 code?

When diagnosing the cause of a P0424 code, a mechanic will use an OBD-II scanner to detect the P0424 code and any other codes that may have been stored, as well. If there are any other codes related to engine misfires, oxygen sensors, or fuel trim, these should be diagnosed and resolved first. One of these could actually be the cause of the P0424 code.

After ruling out one of these codes, the mechanic will inspect for air leaks and test the oxygen sensor. If the code continues to be stored upon retests, the only answer is to replace the catalytic converter.

Common mistakes when diagnosing the P0424 code

The most common mistakes associated with diagnosing a P0424 code involve failing to resolve other codes before addressing the P0424. These other codes can cause major problems for a vehicle, including repeated catalytic converter failure. Failing to address them first can lead to expensive mistakes and more damage to the vehicle.

How serious is the P0424 code?

While you may not notice any difference in how your car drives, a P0424 code can be a serious problem if your vehicle needs to pass an OBD-II emissions test for registration. Not only will a failed catalytic converter cause a vehicle’s emissions to increase, but if the code is not resolved, the Check Engine light will continue to be illuminated, and the vehicle will not be able to pass.

What repairs can fix the P0424 code?

In most cases, after addressing any other codes that have been stored, the catalytic converter will need to be replaced to resolve the code. However, in some cases, other repairs may solve the problem, including:

Additional comments for consideration regarding the P0424 code

If your vehicle is not due for an emissions test, you may be tempted to avoid a potentially expensive repair. However, because other stored codes often trigger the P0424 code, there could be more wrong with your vehicle than you know. Furthermore, when you do need to pass an emissions test, you will need to get this and any other codes resolved so that your Check Engine light is not illuminated at the time of the test.

Need help with a P0424 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
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