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Oxygen Sensors

Frequently Asked Questions

The oxygen sensor, also known as a lambda sensor, is an electronic device that measures the proportional amount of oxygen in a liquid or gas. Every new car and most cars manufactured after 1980 have at least one oxygen sensor. O2 sensors measure the amount of oxygen in your exhaust to determine engine efficiency. Gas engines work by burning an air-fuel mixture in the engine's cylinders. This mixture must be burned in a precise ratio to operate as efficiently as possible. The O2 sensor's job is to help the engine maintain a specific air-fuel ratio that balances power, fuel economy, and emissions. The O2 sensor checks the amount of oxygen in the exhaust compared to the amount in the air. It feeds this information to the engine computer, which then adjusts fuel and air intake.

Simply put, O2 sensors help regulate the air-fuel ratio of your car's engine. Now, there are at least two O2 sensors installed in your car: the upstream sensor and the downstream sensor. Read more.

O2 sensors are always located in the exhaust system. Their function is to detect how much oxygen is left in the exhaust as it leaves the engine and report that information to the vehicle's engine control computer. They are located on the exhaust manifold near the catalytic converter, which is connected to the engine and helps collect emissions. The manifold receives a mixture of air and fuel from the engine.

Because there are two catalytic converters in newer car models, there are two oxygen sensors in a car. The sensor near the engine provides information about the oxygen content in the exhaust before it is processed by the catalytic converter. The O2 sensor located after the catalytic converter, which provides information about the oxygen content after the exhaust has been treated by the catalytic converter. In addition, you can monitor catalyst health.

Step 1: Ensure the safety of your environment

Step 2: Prepare safety goggles, mask and rubber gloves.

Step 3: Allow the engine to cool and jack up the car.

Step 4: Place a shop towel on the floor.

Step 5: Locate sensors.

Step 6: Spray penetrating oil.

Step 7: Remove with your wrench.

Step 8: Fill container with gasoline.

Step 9: Place sensors in container.

Step 10: Add gasoline if necessary.

Step 11: Seal the container and stir.

Step 12: Allow to sit overnight.

Step 13: Lay down a fresh rag.

Step 14: Scrub lightly.

Step 15: Dry with paper towels.

Step 16: Re-install.

Step 17: Dispose of used gasoline.

Although there is a simple list of steps you can follow to clean oxygen sensors, the best method is to simply replace the sensor. No automaker supports sensor cleaning. In fact, you always risk voiding your warranty if you attempt to clean a sensor and something goes wrong later. Read more.

Step 1: Use a multimeter

To get accurate readings, make sure the red and black test leads of your multimeter are plugged into the correct locations. Once these checks are made, you can turn on your multimeter and set the selector switch to ohmmeter until you reach the lowest reading.

Step 2: Disconnect Your Oxygen Sensor

First, identify the location of your O2 sensor. Once you've located your oxygen sensor, you'll need to disconnect it. Make sure it has 4 wires, 2 of which are the same color. You'll then need to test the resistance of these 2 identical wires.

Step 3: Check electrical resistance

To test the electrical resistance of your sensor, you'll need to use your multimeter. Connect it to the two wires of your sensor. The reference value should be between 5 and 7 ohms.

However, the normal resistance voltage may vary depending on the type of sensor you have. If it's a planar or zirconium-based sensor, the ideal voltage value should be between 0.4 and 0.6 V, but it can range from 0.1 to 0.9 V when the motor is hot. If the oxygen sensor is made of titanium, the normal value is 0.5 V.

Step 1: Raise the vehicle

Use a jack to raise each side of the vehicle and place it on jack stands to work safely underneath. Then locate the oxygen sensor(s) on each side of the catalytic converter.

Step 2: Remove the oxygen sensor

To remove the oxygen sensor, disconnect the wiring harness and sensor connector and unscrew the sensor body. Use a degreaser if necessary. Then remove the sensor.

Step 3: Install New Oxygen Sensor

Match the removed sensor to the new one and apply grease to the threads. Install it in its housing, tighten the screw, and reconnect the connector. If the vehicle has a second oxygen sensor, repeat the same procedure, then lower the vehicle to the ground.

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