Oxygen Sensors (O2) - They Monitor The Levels Of Fuel Mixture
Oxygen Sensors (O2) – They Monitor The Levels Of Fuel Mixture

Choose Your Oxygen Sensors (O2) Help Topic Below

(O2) Oxygen Sensor – Function – Failure Symptoms – Testing

Oxygen Sensor (O2) – What Else Could Cause Rich Or Lean Codes

(O2) Oxygen Sensors – Function, Failure Symptoms, Testing Procedures


So, cars with (O2) sensors have a minimum; of one sensor, in front of the catalytic converter. Also, one in each of the car’s exhaust manifolds. But, the actual number of oxygen sensors for a car; depends on the year, make, model and engine size. However, most of the later model vehicles, have four oxygen sensors.

When a gasoline-powered engine burns gasoline, there is oxygen present. So, the oxygen in an engine; is the result of a number of factors. Including, the air temperature; altitude, engine temperature; load on the engine; and barometric pressure. The ideal ratio for oxygen and gasoline is 14.7:1; which slightly varies, depending on different types of gas. In the instance that there is less oxygen present; fuel will remain after combustion. Consequently, referred to as a rich mixture.

Both the rich and lean mixtures are bad for your car; as well as for the environment. A rich mixture results; in a fuel that is not burned. So, a lean mixture generates nitrogen-oxide pollutants. As a result, leading to decreased vehicle performance and engine damage.

Typically, an (O2) sensor creates a voltage; due to a chemical reaction resulting from; an off-balanced gasoline to oxygen ratio. Consequently, most car engines can determine; how much fuel to expel into the engine. As a result, of the voltage of the (O2) sensor. So, if your oxygen sensor fails to function properly; your engine management computer; cannot determine the air to fuel ratio. As a result, the engine is forced to guess how much gasoline to use. Therefore, resulting in a polluted engine; and a poorly functioning vehicle.

Symptoms of a Bad O2 Sensor

So, when an (02) sensor fails, there are a variety of diagnostic trouble codes (DTCs) that can pop up. Most of the time, a faulty (O2) sensor will result in; a check engine light accompanied with a fault code that you can read with an OBD-2 scanner. Based on this fault code, it will point to how it failed and then, move forward with the diagnosis.

Symptoms of a faulty (O2) sensor may include the following:

  • Lean or rich running condition.
  • Poor acceleration.
  • Engine hesitation.
  • Black smoke from tailpipe (rich running condition) black smoke is excess fuel exiting the exhaust.
  • Rough idle.
  • Vehicle stalling out.
  • Reduced fuel efficiency.

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