Chevrolet 12615194 Sensor Assembly, Heated Oxygen (Position 3)(Post, Cat)

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This is because it is either fitted in the exhaust manifold or pipe and due to the fact that both of these freely contract when cold, it might be practically impossible to loosen an oxygen sensor when the engine is cold. Due to the tendency of the sensor to get damaged or the mounting threads on the vehicle, start and run the engine for sometime say about 15 minutes then turn off the engine. Just be careful do not burn your self during the following procedure. Take extra care in the way that you address an oxygen sensor since it contains a permanently installed pigtail and an electrical connector that you cannot unbolt; if they are bumped or detached in any way, then the sensor is done for. Avoid getting any grease, dirt or the like to come into contact with the electrical connector of the heatsink or the louvered end of the sensor; never apply any solvent to it. Oxygen sensors are very sensitive, so they should not be dropped or moved with roughly and the silicone boot covering the sensor should be well fixed to avoid cases of melting and other operational problems. This procedure is used for upstream and downstream sensors which the upstream sensors are positioned at the exhaust manifolds or the upper portion of the exhaust manifold flange and catalytic converter assembly while downstream sensors are found at the lower part of the exhaust manifold/catalytic converter assembly or at the small portion of the exhaust pipe below the catalytic converter. Pull the cable away from the negative batter terminal of the vehicle. To get access to downstream sensors, lift the front of the vehicle and immobilise it with jackstands, and then unbolt the engine undercover. Find the oxygen sensor, follow the electrical lead to the connector and assess the situation, the connector should be unplugged and all harness clips should be removed. Either turning it with a wrench or using an oxygen sensor socket ,the sensor should be loosened and a slotted socket used to remove it. If reinstalling the old sensor when tightening the nuts apply anti seize compound so that next time it will be easy to remove; if replacing the oxygen sensor there is no need to apply anti seize compound because the thread has already got it. Installation is basically the removal's opposite: tightening the oxygen sensor to the proper torque setting is necessary.

An oxygen sensor is a galvanic battery that produces a small voltage output in response to the amount of oxygen in the exhaust gases. This voltage signal is crucial for the feedback loop between the oxygen sensor and the Powertrain Control Module (PCM) to maintain the perfect air/fuel ratio of 14.7:1 that the catalyst needs for optimal operation. All vehicles covered have On-Board Diagnostics II (OBD-11) engine management systems, which means they have the ability to monitor the performance of the catalytic converter. All models covered by this manual have four heated oxygen sensors: one upstream sensor per cylinder bank and one downstream sensor per cylinder bank. Special care must be taken whenever a sensor is serviced, as they are extremely delicate and cannot be dropped or handled roughly. The upstream and downstream oxygen sensors are heated to speed up the warm-up time during which the sensors are unable to produce an accurate voltage signal. The circuit for each oxygen sensor heater is controlled by the PCM. To remove the upstream or downstream oxygen sensor, the vehicle must be raised and securely placed on jackstands. The sensor electrical lead must be traced to the connector and disconnected before unscrewing the sensor with an oxygen sensor socket. If the sensor is difficult to loosen, penetrating oil can be sprayed onto the sensor threads and allowed to soak in for a while. When installing the old sensor, anti-seize compound should be applied to the threads to facilitate future removal. If installing a new oxygen sensor, it's not necessary to apply anti-seize compound to the threads as they already have anti-seize compounds on them. The installation process is the reverse of removal, and the sensor must be tightened to the torque specifications.

An oxygen sensor is a galvanic battery that produces a small voltage output in response to the amount of oxygen in the exhaust gases. This voltage signal is crucial for the feedback loop between the oxygen sensor and the Powertrain Control Module (PCM) to maintain the perfect air/fuel ratio of 14.7:1 that the catalyst needs for optimal operation.

When installing the old sensor, anti-seize compound should be applied to the threads to facilitate future removal. However, if installing a new oxygen sensor, it's not necessary to apply anti-seize compound to the threads as they already have anti-seize compounds on them.

All models covered by this manual have four heated oxygen sensors: one upstream sensor per cylinder bank and one downstream sensor per cylinder bank. The sensors are heated to speed up the warm-up time during which the sensors are unable to produce an accurate voltage signal.