Question 1

What is the general information and replacement procedure for servicing oxygen sensors and air/fuel ratio sensors on 2003 through 2009 Toyota 4Runner?

Accepted Answer

When you are dealing with an oxygen sensor or an air/fuel ratio sensor, the pigtails that are permanently attached to it cannot be unplugged; once the electrical connectors are broken off or pulled off, the sensor is considered unusable. These connectors, the louvered end of the sensor, and any mating surfaces should remain free of grease, dirt and other contaminants, and reagents such as cleaning solvents should not be used on these sensors. One has to be careful not to put too much pressure on the sensors or drop them, and if the sensors use a silicone boot, it has to be fitted appropriately since heat has a potential to melt it and thus making the sensors to function wrong. Altogether there are four oxygen sensors, which one is upstream from the engine and the second is downstream for each cylinder bank. Since these sensors are mounted in an exhaust manifold or pipe which shrinks when cool, they may be rather tight when the engine is cold; if one lubricates the mounting threads with an oil, it will be easier to unscrew them but one has to exercise care not to burn the fingers as the engine is running. First of all, check that the ignition key is off and securely lift the vehicle with help of jackstands. The upstream sensors are positioned on the outlet of exhaust collectours above the upstream catalysts, the left upstream sensor is situated above the left catalytic converter while the right upstream sensor is situated above the right catalytic converter. To replace an upstream sensor, find out the position of the upstream sensor, follow the lead of the electrical wire till the connector and then detach the wire, use a wrench to remove a sensor by unfastening its nuts with anti-seize compound then tighten it with the recommended torque. The process of installation is done in the opposite way as the removal one. The downstream sensors are fitted on the front exhaust pipe assembly upstream the downstream catalysts; the location of the downstream sensor is to loosen the electrical connector and to unscrew the sensor using an oxygen sensor socket or wrench, applying anti seize compound on the threads to tighten them to the specified torque On the installation, the process is reversal to the removal.

Question 2

What is the general information regarding On-Board Diagnostics II (OBD-II) engine management systems and oxygen sensors on 2002 through 2006 Toyota Avalon?

Accepted Answer

OBD-II equipped vehicles with C engine management systems can check the validity of the feedback loop of the oxygen sensor with the PCM with the help of upstream oxygen sensor or air/fuel sensor prior to the catalytic converter and the downstream oxygen sensor located post the converter. The upstream sensor is mounted on the exhaust manifold and the downstream sensor which is heated is installed after the catalytic converter. While distinguishing between oxygen sensors and air/fuel sensors, one should note that the air/fuel concepts function differently, as for the air/fuel sensor, the output voltage depends on the ratio of air to fuel and does not change at the stoichiometric point. The permanently connected pigtail and electrical connector must not be damaged when servicing these sensors; dust and grime should not get in contact with the connector or the end of the sensor; nothing should be poured on these sensors; and they must be handled carefully. Before replacing a sensor one has to warm the engine so as make removal easier, the negative terminal of the battery should be removed and the sensor harness should be reached. The upstream sensor can be easily replaced with out lifting up the car while the downstream sensor will need the car to be supported on jackstands. It is suggested that one should use a slotted socket to do it, anti-seize compound should be applied to the threads of the sensor before assembly. Finally the sensor is safely locked in place and the electrical connector joined back, the vehicle should be lowered, as well as tested on the road so that there is no trouble code existing.

Question 3

What is the general information about On-Board Diagnostics-II (OBD-11) engine management systems and oxygen sensors on Toyota Sienna?

Accepted Answer

All OBD-11 equipped vehicles use engine management systems to highlight the consistency of the feedback loop between the oxygen sensor and the PCM using an oxygen or air/fuel sensor before the catalytic converter and another oxygen sensor after it to give PCM a record regarding converter efficiency. These models include three sensors; with upstream sensors located in the exhaust manifolds as well as a downstream sensor placed after the catalytic converter while the upstream sensors differ with region and year, air/fuel sensors are used in models produced after 2001. The principle of oxygen sensors working as galvanic batteries is operationally linked with the PCM which controls the air/fuel mix depending on the voltage output; the effectiveness is related to electrical connections, no blockage to air to the sensor, the right operating temperature, and if the fuel used is unleaded. If the oxygen sensor provides a stable voltage less than 1.45 volts as RPM increases when the engine has normal temperature, PCM will store a trouble code. In the event of administration failure of the different sensors, the PCM switches to open loop control of fuel. Likewise, the air/fuel sensor is also an interface between the PCM as it reports a variable voltage which is proportional to the AFM, similar to the function of an oxygen sensor but first needs warm up. Measures that should not be taken during servicing of the sensor include; damage of the attached pigtail and an electrical connector, exposure of the sensor to contaminants, and use of cleaning solvents on the sensor part, and proper handling of the sensor with integrity.

Genuine Toyota Oxygen Sensor

658 Oxygen Sensors found

Toyota Air Fuel Ratio Oxygen Sensor

Toyota Air Fuel Ratio Oxygen Sensor

Toyota Air Fuel Ratio Oxygen Sensor

Toyota Oxygen Sensor

Toyota Air Fuel Ratio Oxygen Sensor

Toyota Air Fuel Ratio Oxygen Sensor

Toyota Oxygen Sensor

Toyota Air Fuel Ratio Oxygen Sensor

Toyota Oxygen Sensor

Toyota Oxygen Sensor

Toyota Air Fuel Ratio Oxygen Sensor

Toyota Air Fuel Ratio Oxygen Sensor

Toyota Oxygen Sensor

Toyota Air Fuel Ratio Oxygen Sensor

Toyota Air Fuel Ratio Oxygen Sensor

Toyota Air Fuel Ratio Oxygen Sensor

Toyota Oxygen Sensor

Toyota Oxygen Sensor

Toyota Air Fuel Ratio Oxygen Sensor

Toyota Air Fuel Ratio Oxygen Sensor

About Toyota Oxygen Sensor

Toyota Oxygen Sensor Parts Questions & Experts Answers

Related Toyota Parts

Browse by Model