A Honda Civic has two sensors that read the oxygen levels in the exhaust when the engine is running. The oxygen level data is used by a Honda Civic computer to control the fuel supply and ignition. Located before and after the catalytic converters, the sensors can malfunction and cause the motor to lose power. A bad oxygen sensor can result in an engine light indicating that something needs to be fixed, a malfunctioning engine that blows smoke out of the exhaust fails an emissions test or does not work at all. Change an oxygen sensor in a Honda Civic using an oxygen sensor socket and some penetrating oil.
- It applies penetrating oil around the base of the defective oxygen sensor, where it is screwed into the exhaust pipe or the exhaust manifold. The Honda Civic has two sensors that control the exhaust gases produced by the engine during its operation. One sensor is located before the catalytic converter and the other one after it. The former can be found by removing the exhaust manifold and the other out of the exhaust fumes near the silencers. Depending on which sensor is wrong, you will be working inside the engine compartment or under the vehicle.
- Disconnect an oxygen sensor from the wire harness on the cable adapter that holds it in place. The wiring adapter has a tab that locks two connectors together and needs to be unlocked to separate the sensor connector from the harness connector. Lift the tongue and separate the adapters. The sensor and its cable can be removed without twisting the harness cables while the sensor is rotated inside the threaded collar when removed.
- Place an oxygen sensor socket on top of the sensor. These connectors have space for the sensor cable to pass through the side of the socket, allowing it to be placed around the sensor and the sensor to be loosened from its position on the sensor mounting collar. Turn the socket counterclockwise to loosen the sensor inside its threaded mounting collar.
- Unplug the entire sensor when it has loosened enough to be removed by hand, or continue turning the sensor and socket counterclockwise until it is clear of the threaded collar that holds it in place.
- Remove the sensor and discard it correctly. Oxygen sensors use precious metals to read the oxygen levels in the exhaust gases. These sensors must be recycled successfully.
- Insert a new oxygen sensor into the threaded neck of the sensor by hand until it is tight. Place the sensor connector on top of the new sensor, and use the ratchet wrench to continue tightening it. When the sensor has been well reinforced, connect the new sensor to the old wire harness using the latest sensor wiring adapter.
On hard-to-remove sensors, use a torch to gently heat the threaded neck where the sensor is located to help loosen it for removal. The heat will expand the collar enough to allow the sensor threads to be released from the threaded collar. If you do not have a blowtorch, run the vehicle at its operating temperature.
Exhaust from a Honda Civic will be very hot if you run the vehicle before changing the oxygen sensors. Because most sensors are difficult to remove, heat is usually applied to obtain their release. When heat is added to the exhaust, it becomes hot enough to burn the skin long after the heat has been used. Avoid burns by wearing gloves and protective clothing.