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P0134 Fault Code


You can find information about the P0134 fault code on this page.

It is one of the most popular fault codes that people search for on this website (in the top 50).

We have given it a seriousness of 7/10 with 1 being the least serious and 10 being the worst.

P0134 Short Description

"O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1)"

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Description Icon Long Description

Fault code P0134 is logged when the engine control unit (ECU) has detected a malfunction with the bank 1 oxygen sensor 1. This happens when the heated oxygen sensor is not sending any signals to the ECU.

This fault code typically indicates a faulty upstream heated oxygen sensor.

A heated oxygen sensor is used to monitor the air-fuel ratio found in the exhaust gases. These sensors help determine the level of emissions that are being produced by the engine.

If the sensor is not providing the ECU with any information about the air-fuel mixture in the exhaust fumes, the ECU will be unable to optimize the air-fuel mixture in the combustion chamber.

Sensor 1 is considered the upstream heated oxygen sensor. Bank 1 refers to the side of the engine where cylinder 1 is located. This is only applicable to V-shape engines.

Manufacturers like Acura, Dodge, and Honda are some of the most commonly reported to have this issue.

However, all modern vehicles have this heated oxygen sensor, making it possible for any vehicle to log this fault code.

Warnings Icon Other Signs of This Problem

There are usually only a few signs of an issue with a heated oxygen sensor. This makes it important to look out for the presence of the Check Engine light and the subsequent fault codes being logged.

With no reading from the oxygen sensor, it is possible the engine will have noticeably higher emissions. This can come in the form of black smoke from the exhaust.

There can be other issues with how the engine is running as well. Lower fuel economy is one of these signs as the engine is not optimally using its fuel.

The engine can also run poorly.

If these symptoms are present but P0134 has not been logged, look out for its mirror code P0154. It is also a good idea to look out for fault codes from the downstream sensor like P0140.

Broken Down Icon What Could Be The Problem?

In the case of P0134, it is likely that the sensor itself is the cause of the issue as it is not sending any output signal.

A faulty sensor can easily cause this. Additionally, any issues with the wires or connections can cause a breakdown between the sensor and the ECU.

In some instances, a leak in the exhaust or vacuum can cause no reading to be detected by the heated oxygen sensor.

Very rarely, the ECU can be the cause of this issue.

Fixed Icon Fixes

The fixes for P0134 will mostly focus on getting the heated oxygen sensor to provide an accurate output signal. This can mean fixing issues in the heated sensor circuit or fixing issues upstream that are causing the sensor to miss information.

One of the most likely fixes is that the heated oxygen sensor needs to be replaced. If the heated oxygen sensor is faulty, it should be replaced. This can be done by checking the resistance and voltage of the sensor.

Any leaks in the exhaust should be fixed. These will typically be found upstream of the sensor.

If the ECU is faulty, it must be replaced. Software updates can also help here.

Danger Icon Seriousness

Fault code P0134 should be considered a moderately serious issue. In some instances, this code can result in damage to the catalytic converter, which can be an expensive fix.

It is best to have this issue fixed as soon as possible.

P0134 Image

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