Toyota Tacoma P0430 Code: Causes + How to Fix

This page is meant to help you troubleshoot the Toyota Tacoma P0430 trouble code. It covers the P0430 code’s meaning, symptoms, causes, and possible solutions.

P0430 is an emissions-related trouble code and is virtually never a breakdown risk.

P0430 is usually caused by a catalytic converter issue or a bad O2 sensor.

Table of Contents

Toyota Tacoma P0430 Quick Info Table

Toyota Tacoma P0430

DefinitionP0430: Catalyst System Efficiency – Below Threshold (Bank 2)
SymptomsCheck engine light
Common CausesBad catalytic converter, O2 sensors
Breakdown Risk?Rarely (it’s an emissions code)
Repair Cost (Parts)$250 or less
Repair DifficultyO2 sensor replacement is easy, but the catalytic converter can be a challenge

P0430 OBDII Code Defined

P0430 is generic (has the same meaning for all vehicles made in 1996+) OBDII trouble code. Here’s the technical definition for your Toyota Tacoma:

P0430: Catalyst System Efficiency Below Threshold (Bank 2)

Catalyst System Efficiency

Your Tacoma’s exhaust contains hydrocarbons, carbon monoxide, and other harmful gasses. Catalyst system efficiency measures how many chemicals are removed from the exhaust system. A modern catalytic converter should pull over 95% of these pollutants out.

Oxygen sensors measure the gasses that enter and exit your Tacoma’s catalytic converter.

Efficiency Below Threshold

P0430 Definition Toyota Tacoma
An upstream O2 sensor

When the readings from the upstream and downstream oxygen sensors show similar readings (not enough pollutants expelled from the exhaust), your truck will throw the service engine soon light (P0430).

These readings shouldn’t match since your Tacoma’s catalytic converter is scrubbing the pollutants from the exhaust.

When the readings from each O2 sensor get close, the software in your Tacoma’s PCM believes that the catalytic converter is no longer doing its job. This can happen for three reasons:

  1. The exhaust is escaping before it is measured.
  2. The catalytic converter is losing efficiency and needs to be replaced.
  3. The O2 sensors are not reporting the right readings from the exhaust.

Bank 2

Bank 2 is the side of your Tacoma’s engine with the second cylinder. Typically, the first cylinder is closer to the front of the engine.

A quick Google search for your truck’s engine and model year can quickly confirm that. The bank 1 version of this code is P0420.

Toyota Tacoma P0430: Symptoms

P0430 Symptoms

The P0430 code in a Toyota Tacoma will often be thrown if one of your truck’s oxygen sensors is not functioning correctly.

There are rarely drivability issues associated with P0430. For most people, the first sign that anything is wrong is the service engine soon light coming on.

Here are the typical symptoms that something is wrong when you have code P0430:

  • Service Engine Light– Often, this is the only symptom.
  • Rotten Smell– A rotten egg or sulfur smell is a telltale sign of a bad catalytic converter.

P0430 Causes

P0430 Causes Diagnosis

Here are the most common causes of P0430 in the Toyota Tacoma:

Likely Causes

  • Bad catalytic converter
  • Bad O2 sensor

Other Causes

  • Exhaust leak
  • O2 sensor wiring
  • PCM issue
  • Overheating converter (usually caused by a misfiring engine, there should be codes)
  • Burning oil (overheats converter, usually no code)
  • Engine not heating up enough

P0430 Diagnosis

The most common fix for P0430 in the Toyota Tacoma is a new catalytic converter, followed by replacing the Oxygen sensor. Before taking your Tacoma into an exhaust shop for a new catalytic converter, let’s ensure that’s what you need.

Here’s a good P0430 diagnostic order for the Toyota Tacoma:

1. Check for Other Codes

The first thing you want to do when trying to fix P0430 in the Tacoma is to verify there aren’t any other trouble codes. Three types of codes can give clues as to what’s going on with your truck.

Misfire Codes

If you have a misfire-related code (such as P030X, where X is the misfiring cylinder) or P0300 (random multiple misfiring), it can cause the catalytic converter to overheat, which decreases its efficiency and throws P0430.

The misfire code should be for cylinder 2, 4, 6, or 8 (if applicable).

Engine Temp Sensor Codes

If your Tacoma’s PCM doesn’t know the engine temperature, it’ll keep the fuel mixture rich. When this happens, the exhaust the O2 sensors see will be out of range, and it could throw P0430. You should see P0128 and (likely) P0420 along with this code.

O2 Sensor Codes

If your truck has any O2 sensor-related codes, jump to section three.

2. Exhaust Leak (Easy to Check)

Toyota Tacoma P0430 Fix

It would be a good idea to check your truck for an exhaust leak first. You should be able to hear it easily when looking underneath your Tacoma.

An exhaust leak can cause P0430 since it causes exhaust gasses to escape unmetered.

If your truck doesn’t have an exhaust leak, you’ll need to test the O2 sensors and/or catalytic converter.

3. Test the Oxygen Sensors

Toyota Tacoma Bad Oxygen Sensor Symptoms
Typical Oxygen Sensor

Your Toyota Tacoma has at least two oxygen sensors, one before and one after the catalytic converter (commonly referred to as the upstream and downstream O2 sensors).

  • Upstream– The upstream (before the exhaust gas hits the catalytic converter) oxygen sensor measures the exhaust gasses as they exit the engine. The Powertrain Control Module (PCM) uses this data to adjust the air-fuel ratio, ignition timing, and more.
  • Downstream– The downstream oxygen sensor’s (after the exhaust exits the catalytic converter) primary function is to verify the catalytic converter is doing its job.

Often, an oxygen sensor is the cause of P0430. When an oxygen sensor has failed, it can cause a false reading and trigger this code in your truck. You can test the sensor before replacing it. The videos below show you how to test one with a multimeter or professional scan tool.

How to Test an Oxygen or O2 Sensor (YouTube: Multimeter and Torch)
How to Check the O2 Sensors (YouTube: Scan Tool)

4. Inspect the O2 Sensor Wiring

P0430 Fix Toyota Tacoma

Over time, the oxygen sensor wiring can go bad. It is especially volatile since it is right next to the hot exhaust at all times. The downstream oxygen sensor wiring is also fragile since it is far from the ECM, and the catalytic converter can get hot (more distance to travel = more area to fail).

How to Test Wiring in Under an Hour (2 Car Pros)

5. Catalytic Converter (Most Common)

The catalytic converter is responsible for scrubbing out as much pollution as possible from your Toyota Tacoma’s exhaust.

Over time, it can lose its ability to strain pollutants out of the exhaust. Although modern catalytic converters are supposed to last the life of most vehicles, over time, they can lose their ability to strain pollutants out of the exhaust.

There could be some underlying problem if it has clogged, such as a misfire, an air/fuel mixture that is too rich, or oil getting into the cylinders. You can test your catalytic converter with a heat gun to see if it’s overheating (see how in the video linked below).

How to Test Your Catalytic Converter in 15 minutes (YouTube)

A Quick and Easy P0430 Test

You can determine if P0430 is caused by a bad oxygen sensor by swapping the bank one O2 sensors with the bank two O2 sensors. If the code changes to P0420, that would indicate that one of the O2 sensors is bad on the bank 2 side.


If there are no codes other than P0430 present, and the O2 sensors are recording data properly, it’s likely your Toyota Tacoma’s catalytic converter has failed, which is what this code is reporting.

P0430 shouldn’t affect the drivability of your truck, but it’ll fail an emissions test.