Honda Civic O2 Sensor Replacement Guide
Is your Honda Civic’s check engine light on, are your emissions reaching high levels, and does black smoke come from your exhaust? Learn how to fix the problem by replacing the Oxygen Sensor of your Honda Civic.
Even though oxygen sensors are not particularly maintenance items, they often start to fail around the 100,000 to 150,000-mile mark on modern Honda vehicles. Once it fails, the check engine light will come on and stay on, and a decrease in fuel economy.
Are you more of a visual learner? Check out our video guide below!
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Procedure
- Park your Honda on level ground and allow the engine to cool down.
- Open the hood when replacing the upstream oxygen sensor (Bank 1 Sensor 1 or Bank 2 Sensor 1). If you are replacing the downstream oxygen sensor (Bank 1 Sensor 2 or Bank 2 Sensor 2), you should jack up the vehicle as these sensors are accessed from the bottom of the engine.
- Locate the oxygen sensor on your Honda engine. The upstream oxygen sensor (Bank 1 Sensor 1) is mounted on the exhaust right before the catalytic converter. Bank 1 Sensor 2 is mounted after the catalytic converter and can be accessed from under the car.
- Disconnect the oxygen sensor wire harness. Use an oxygen sensor socket to remove it from the catalytic converter. Turn the socket counterclockwise to remove the O2 sensor.
If it doesn’t come loose right away, spray penetrating oil near the threads and let it soak for at least fifteen minutes. - Remove the oxygen sensor.
- Install the new part. Apply a small amount of anti-seize to the threads and hand-tighten the sensor in the exhaust. Using a torque wrench, tighten the new piece to 33 ft-lb. If you don’t have a torque wrench, use a ratchet to tighten the oxygen sensor until it is snug.
- Connect the electrical connector by pressing the two ends until they click.
The upstream oxygen sensor (Bank 1 Sensor 1) is mounted on the exhaust right before the 
If it doesn’t come loose right away, spray penetrating oil near the threads and let it soak for at least fifteen minutes.
We replaced the upstream oxygen sensor, which is accessed from the top of the engine. You can follow these to replace the downstream oxygen sensor, but that sensor is easier to access from the bottom of the engine.
Symptoms
When your Honda oxygen sensor fails, you will decrease in performance, such as:
- A decrease in fuel mileage.
- Difficulty starting.
- Check engine light on.
- Loss of power.
- Excessive smoke from the tailpipe.
- Failed emission (smog) test.
- Hesitation, poor acceleration.
- Rough idle.
- Possible codes P0420, P0135, P0141, P0155, etc.
Use an OBD-II scanner to read the codes via the OBD-II port under the dashboard to confirm the oxygen sensor is defective.
Check Engine Light Still On
If the check engine light remains on after replacing the Oxygen Sensor, you can use the YOUCANIC Full System Scanner to clear the stored codes. This scanner can also read and clear fault codes through every control module of the Honda vehicle.
Frequently Asked Questions
How often should I change my oxygen sensor?
It should be replaced when it fails. In many cars, oxygen sensors typically fail between 100,000 and 150,000 miles.
Can a bad O2 sensor cause a P0420 code?
Yes. The P0420 code indicates that the catalytic converter is operating below its threshold. This code appears when the catalytic converter is faulty or the oxygen sensor is defective.
Can I use a universal oxygen sensor?
Yes, you can. You may have to splice wires and will need to connect all four wires correctly. The new connections tend to corrode and cause problems down the line. Make sure to insulate the wires properly.
What is the Honda O2 sensor thread size?
The most common Honda oxygen sensor thread is 18 mm x 1.5 mm.
What are some symptoms that my Honda oxygen sensor is bad?
Check engine light and poor fuel economy are the most common.
What socket size is used on the Honda oxygen sensor?
7/8″ or 22 mm socket.
Is it legal to use an oxygen sensor spacer?
No. In most countries, it is not legal to install an oxygen sensor spacer.
Honda oxygen sensor wire colors?
The typical color on the OEM Honda O2 sensor.
The ground will be green or gray.
The signal is white or black.
We hope you find the Honda Civic O2 Sensor Replacement Guide helpful. Check these troubleshooting and repair guides for more help on your Honda Civic.
