It"s no a component you think about often, yet the air/fuel ratio sensor performs and important duty as a part of your car"s emissions system. Below is the 411 on air/fuel ratio sensors.

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Understanding Air/Fuel proportion Sensors

An air/fuel ratio sensor is lot like an oxygen sensor, or O2 sensor, and is progressively replacing them on many vehicles. Particularly today"s much more sensitive, turbocharged, and also efficient engines. Unequal the breakable O2 sensor, one air/fuel proportion sensor is a wide selection sensor quite than small range, and also it operates by conduction quite than generation and is thus slightly more accurate. Prefer oxygen sensors, though, air/fuel proportion sensor will be positioned before and after the catalytic converter top top OBDII-compliant engines (Sensor 1 is constantly on the exhaust manifold, Sensor 2 is always after the catalytic converter) and also will be referred to as O2 sensors in most of the OBDII literature, despite being air/fuel proportion sensors.

Benefits the Air/Fuel ratio Sensors:

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Air/Fuel proportion Sensor vs. O2 Sensor


The two distinctions in how an air/fuel proportion sensor functions versus the enlarge O2 sensor renders all the difference in just how they function to aid the electronic regulate module (ECM or ECU) track the engine"s performance.

The larger O2 sensors have actually a main core do of zirconium (or, in rare cases, titanium) which create voltage when oxygen molecules pass v it. The new air/fuel proportion sensor offers a double core and committed electronic circuitry to regulate current flow. The twin core acts together a conductor into which the air/fuel proportion sensor"s circuitry sends out current. The an initial of the dual cells, called the pump cell or diffusion chamber, receives waiting from the exhaust stream. Oxygen in that stream determines the conductivity the the cell, creating current distinctions from the which is being sent out by the air/fuel ratio sensor"s circuitry and also being received back in the circuit. The second cell, the recommendation cell, residences outside air for referral in the calculations do by the ECM (engine manage module).

This enables a broader band the measurement and also a an ext precise measure of what"s happening in the exhaust currently in real-time. That also enables for faster adjustment. The ECM can readjust the pulsation-reduction to bring the mixture back to lean or widens injector pulsation to include fuel once the output is wealthy in oxygen. The air/fuel proportion itself can additionally have that current adjusted and also reversed in polarity in order to "suck in" or expel excess oxygen indigenous the Pump cabinet to clean it for new measurements.

All of these operations have the right to be done several times every second, enabling for very precise control over the engine"s output and also emissions. The alters in voltage the the air/fuel ratio sensor measures are minuscule, ~ above the bespeak of milliamps, giving them high precision because that measurement, but likewise making it an overwhelming to check the air/fuel proportion sensor because that diagnostics.

Testing should be done utilizing a scanner made for the objective or a more recent OBD scanner that has this functionality. In-line scanning via a meter is not possible with an air/fuel ratio because of the low transforms being measured and also the need that lines it is in cut and also spliced to make the dimensions (which could affect the input/output with included interference). That is important to recognize the regular operating voltage for the vehicle"s air/fuel proportion sensor, usually in the volt range, and how your scanner will analyze the results -- which might be in really amp alters or in lambda ratios (starting at 1.0 together ideal). Greater numbers are lean, reduced numbers room rich matching to the conduction difference in the Pump Cell.

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The Bottom line on Air/Fuel ratio Sensors

Manufacturers are relocating towards air/fuel ratio sensors since they provide a faster, an ext control-able emissions regulate option, permitting a an ext continual optimal air:fuel ratio (usually organized at 14.7:1 in a gasoline engine). Whereby an enlarge O2 sensor might require more than a 2nd to reason adjustments and calibration for air:fuel, one air/fuel ratio sensor permits it to be done in fountain of a second instead, greatly raising economy.