SOURCE: i have a toyota rav4 2003 management light came on
The upper sensors are air fuel sensors and the lower ones are o2 sensors. you cant mix these up. Assuming you did everything right and still coding then either the new sensor b1s2 is bad or the wirng(power and ground need to be checked. A scan tool can be used to look at the performance of the sensors too. Sometimes the codes just point to the area of the problem and changing the part isn't the answer.
SOURCE: HI I have toyota avensis verso
Air/Fuel Sensor Heater Circuit. (Bank 1 Sensor 2)
The A/F sensors are positioned high in the manifold before the cat and are used to make adjustments to the air/fuel ratio of the fuel injection system. The heated oxygen sensors are positioned after the cat and check the efficiency of the cat (what happened in there as a result of the A/F sensors above). They too can signal changes to the air/fuel ratio. These latter sensors only work when they are hot and need to be electrically heated quickly to give decent information quickly. They work by comparing the oxygen inside the exhaust with the oxygen on the outside.
You could say that the ones before the cat make large adjustments and the ones after make smaller refinements.
It is worth remembering that a fault code could have been stored because at some stage the sensor went outside of its range and for this reason it is always worth cancelling any stored codes as this sometimes puts the light out. There are also several other reasons why a sensor could be showing a fault (it is correctly saying that something else is causing incorrect air/fuel ratio) such as leaky EGR valves or vacuum pipes so just have a look around to see if there is anything obvious.
The DTC code will normally indicate the exact sensor that is faulty or at least showing out of range and not the group of sensors. In this case as you stand looking at the engine from in front of the car it is the top one on the drivers side.
Keep in mind they are sensitive devices (read that as fickle) and although you should start there you can often end up changing more than one and some cases even the cat before you can get them to settle down.
Good luck.
SOURCE: i have found the code
Hi, assuming you have the 4-cylinder engine, this is your downstream oxygen sensor. Look carefully at the picture to find the right sensor, as there are several similar sensors on the truck. Before buying a new sensor, check the resistance of the heater in the sensor by disconnecting the sensor and connecting an ohmmeter to the terminals indicated in the second picture. The resistance should be 11-32 ohms, depending on the temperature (if the truck is hot from running, the resistance should be at the higher end of the range). If the resistance is outside this range, replace the sensor. You'll need a line wrench or special socket to remove the sensor, as the pigtail is an obstacle to a regular deep well socket. Please let me know if you have more questions, and thanks for using FixYa.
SOURCE: how do you change an air/fuel sensor heater circuit (bank1, sensor2)?
The heater is part of the sensor assembly, the usual fix is to replace the A/F sensor , in this case bank one is near the firewall and sensor 2 is just behind the catalityc converter for bank one.
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