Mazda 3 Check Engine Light Codes To Beware

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A Mazda 3 has several warning lights that can appear on the dashboard, but when the check engine light comes on, you might find yourself starting to panic. Are you about to break down? Is something seriously wrong? A check engine light can put a damper on any Mazda 3 owner’s day. However, knowing the various reasons that can cause this annoyance can help put your mind at ease. 

Check Engine Light Mazda 3 Basics

A check engine light, also known as the malfunction indicator lamp, appearing on your Mazda 3’s dashboard can be scary, especially on a long drive. Luckily, it is typically only a moderately urgent issue. The Mazda 3 check engine light illuminates when the On-Board Diagnostic (OBD) system senses something wrong with the engine, transmission, or the evaporative emission control system. 

It can indicate something as simple as extremely low fuel or a loose gas cap, but it can also come on for more serious concerns with the used Mazda engine or transmission. The important thing is not to panic and try to get to the root of the issue. 

Diagnostic Trouble Code

When the check engine light appears, your Mazda 3’s OBD system stores a Diagnostic Trouble Code, also known as a fault code, to help with diagnostics. You will need access to diagnostic equipment such as an OBD-II scanner to see and decipher those codes. A diagnosis port is located on the driver’s side of the Mazda 3 under the dashboard. If you don’t have diagnostic equipment, you can take your Mazda 3 to a local dealership or auto parts stores such as AutoZone, O’Reilly, and Advance Auto Parts. 

Common Mazda 3 Check Engine Light Codes

Code P0126 

This code indicates an issue with your Mazda 3’s coolant temperature. A likely cause for this Mazda 3 Check Engine Light Code is the thermostat being stuck in the open position, which makes your engine unable to reach the proper operating temperature. 

Codes P0012 and P0014

These two check engine light codes indicate an issue with your Mazda 3’s timing chain. It can be caused by a dirty VVT filter screen. Another reason the timing chain code may appear is if your Mazda 3 has a faulty solenoid.

Code P0171

This Mazda 3 check engine light code is often accompanied by rough idle, hesitation during acceleration, and lack of power. It typically indicates an issue with a dirty mass air flow sensor, which causes false air flow readings. This code can also indicate an intake leak. 

Code P0455

If a strong gas smell joins your Mazda 3 check engine light, you may look at an evaporative emission control system leak. The leak could be in the purge valve or the fuel tank pump union nut. Deterioration and even breakage can occur in the evap system over time, so it is essential to check if this code appears. 

Codes P0420 and P0431

While these codes can indicate a much more expensive catalytic converter issue, it could be something simple like a faulty oxygen sensor. If your Mazda 3 check engine light code is one of these, it would be beneficial to check the oxygen sensor before looking at the catalytic converter. 

Codes P0300, P0301, P0302, P0303, P0304, P0305, P0306

These Mazda 3 check engine light codes indicate an issue with a spark plug, spark plug wire, or ignition coil. If your Mazda 3 has over 100,000 miles and you haven’t changed your spark plugs, it is past time to do so.

A Flashing Check Engine Light

If your Mazda 3 check engine light is flashing, that indicates a more urgent issue, and the car should not be driven because it could damage the engine. If it must be driven, it is not recommended to operate at high speeds. If the check engine light is flashing instead of stagnant, there is a misfire on one or more of your cylinders. 

Mazda 3 Check Engine Light Reset

It is possible to get the check engine warning light to disappear from your dashboard by disconnecting and reconnecting your Mazda 3’s battery. Simply turn off the ignition, disconnect the negative terminal of your car’s battery, wait for 15 to 30 minutes while pressing the horn every few minutes, and reconnect the negative terminal.

When you start your Mazda 3, the check engine light should be gone. However, this is not recommended by any professional Mazda 3 technician because it can hide important issues. The best solution is to visit a certified Mazda technician to diagnose and fix the problem. 


A Mazda 3 check engine light can indicate many different issues, some simple and some more complicated fixes. No matter the case, the check engine light lets you know there is a problem with your vehicle, and it is important to take it to your local dealership or automotive store to run diagnostics.

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