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P0131 – O2 Sensor Circuit Low Voltage

P0131 error code

Oxygen sensors like any component of your vehicle can wear and fail over time. When this happens one of the most common OBDII trouble codes that trigger the check engine light is P0131. This trouble code signifies that there’s a signal from your oxygen sensor that’s lower than what your ECU expects. This can negatively impact your gas mileage, and cause several P0131 issues that can ruin your day.

The primary function of your oxygen sensor or the 02 sensors is to read the air-fuel mixture of your exhaust. By measuring the oxygen content in the exhaust gases, your PCM or ECU can accurately adjust the fuel being delivered by your fuel injectors.

This can cause a lot of problems for your vehicle. The biggest headache that the P0131 trouble code can present is that you will fail your emissions test. When this happens you need to get the facts to fix P0131 trouble code issues right away.

What does the P0131 code mean?

The verbiage behind the OBDII P0131 trouble code is a low sensor voltage for your oxygen sensor bank. This check engine light is for sensor 1 or bank 1, and it implies that your ECU or onboard computer sees an improper air-fuel ratio.

Combustion engines produce emissions, and that’s what your oxygen sensor reads to adjust fuel trims. This reading is vital to ensure that your vehicle is running optimally. When your 02 sensors aren’t functioning properly, your check engine light will turn on.

This is because your onboard computer is designed to help produce as little air pollution as possible, and to maintain fuel economy. When the oxygen sensors are sending a voltage lower than what your ECU expects, your vehicle is running blind.

P0131 Symptoms

If your check engine light is on and your OBDII scan tool is reporting a P0131 error code, there are some obvious symptoms. These errors will cause your vehicle to run poorly, and could even cause starting issues.

First, your ECU will believe that your engine is running lean. This will increase the amount of fuel delivered to the engine, which will waste gas and could potentially foul your catalytic converter.

Common Problems That Trigger the P0131 Code

Most Air Fuel Ratio Sensors are basically two heated Oxygen Sensors that work in tandem in order to create a much faster responding Oxygen Sensor/Fuel Control System. A conventional Oxygen Sensor System cannot maintain fuel control when the throttle is above 50 percent and the vehicle is under heavy loads, such as wide-open throttle.

When the code P0130 is set, record the freeze frame data in fine detail. Next, duplicate the code setting conditions on a test drive, paying particular attention to load, MPH, and RPM.

The best tool to use on this test drive is a data streaming scan tool that has factory quality and dedicated live data. When you can read the live data from the oxygen sensor, you can accurately determine if your 02 sensor ha failed.

Replace your oxygen sensor and use the scan tool to erase your P0131 error code. Learn how to fix check engine light errors by subscribing to My Pro Street for all the latest How-To Guides and DIY articles.

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