[Guest]

I am asking you experts out there if anyone knows if rav4 v6 eng has both o2 sensors and air fuel sensors.The dealer mechanic says it shows both codes.After he reset ecu and changed 02 sensor the air/fuel showed up.Does that sound right.please comment if you know about this.My original post was Dec 20.I have looked through past posts concerning this buy I may have missed this one.thanks

 

[LdyDee]

Toyotas have both

 

[RAV4Don]

It is my understand that an 02 sensor and an air/fuel sensor are similar terms for the same set of sensors. I am not aware of any sensor that "senses" fuel per se. The O2 sensors monitor the level of O2 in the exhaust and adjust the injector pulse width (adding or substracting fuel) to maintain the optimal fuel to air ratio.

 

[Nismopowered]

On all 3 engines the upper or number 1 sensors are air fuel ratio sensors, the lower or number 2 sensors are o2 sensors.

 

[RAV4Don]

On all 3 engines the upper or number 1 sensors are air fuel ratio sensors, the lower or number 2 sensors are o2 sensors.

Nismo are you referring to the pre catalytic and post cat O2 sensors? Can you elaborate? The O2 sensor post cat is there simply to monitor the operating effectiveness of the the pre-cat O2 sensor. In other words this second O2 sensor is more for emission (OBDII) purposes and is not part of the engine management system.

 

[Nismopowered]

The precat are a/f sensors. The after cat is to moniter the cat not the front sensor. They are o2 sensors. The front should be an oscolating signal, always moving .01-1.0 volts. If the cat is working the rear will be a steady signal. If the rear sgnal flucuates then the ecu knows that the cat is not working.

 

[RAV4Don]

The precat are a/f sensors. The after cat is to moniter the cat not the front sensor. They are o2 sensors. The front should be an oscolating signal, always moving .01-1.0 volts. If the cat is working the rear will be a steady signal. If the rear sgnal flucuates then the ecu knows that the cat is not working.

Yes, that is how I understand it works, although i may not have stated it very well. But it is the term "a/f sensor" that puzzles me. Is this not an O2 sensor on Toyotas like on all other OBDII vehicles? I am not aware of any sensor that monitors 'fuel'. O2 sensors only read the amount of O2 in the exhaust gases, they do not measure any fuel. Correct? Is Toyota's use of the term a/f sensor merely meant to indicate a typical wide band O2 sensor?

 

[Nismopowered]

I think that the air fuel ratio sensor is the same as a wideband o2 but im not positive. As I know they work the same as an o2 but just do it better.

 

[RAV4Don]

I think that the air fuel ratio sensor is the same as a wideband o2 but im not positive. As I know they work the same as an o2 but just do it better.

Yes, that is what I believe. In Toyota speak, air fuel sensor = wide band O2 sensor.

 

[Guest]

If I may jump back in the conversation betweem Rav4Don and nismopowered. There is a lot of good info there guys. Does all this mean I have an 02 sensor and air/fuel ratio sensor on each eng bank for a total of 4 on eng side plus cat converter.This seems to be what I gathered,The troubling thing is my 4wd,cruise control and vsc are disabled by an eng error that would seemingly have nothing to do with other functions.Any ideas on this?I cant get an answere from dealer other than thats how it is setup.appreciate the info and keep it coming.

 

[Nismopowered]

4cl 1 a/f before cat and 1 o2 after cat
6cl 1 a/f on each manifold before cat(1 front, 1 rear) and 1 o2 after cat on each side.

1 each for the 4 and 2 each for the v6.

Can you post what codes you have?

 

[Guest]

thanks for the info nismopowered. the original code was po158. after 02 sensor changed. code and ecu reset the code that came up according to mech was a/f sensor. he did not say what that code was. i will ask when i go back to have the a/f sensor replaced also.thanks

 

[friendly_jacek]

It is my understand that an 02 sensor and an air/fuel sensor are similar terms for the same set of sensors. I am not aware of any sensor that "senses" fuel per se. The O2 sensors monitor the level of O2 in the exhaust and adjust the injector pulse width (adding or substracting fuel) to maintain the optimal fuel to air ratio.

Hmm. I guess you did not get the explanation given back in 2008?

http://rav4world.com/forums/viewtopic.php?t=16513&highlight=

 

[Myxalplyx]

Yes, that is what I believe. In Toyota speak, air fuel sensor = wide band O2 sensor.

Old Thread! Late thank you. It's the 2nd one that I have read that indicates we have a wideband O2 sensor on our vehicle. If that is the case, I won't waste time purchasing one.

 

[vasillalov]

The O2 sensor is used for calculating air-to-fuel ratio. How?.. The ECU knows precisely how much fuel enters in each cylinder because it controls the injector pulse for every cylinder. It also knows how much air went in because the MAF sensor reports it. Yet, this is still not enough to ensure that the combustion event occurred at maximum efficiency. If the spark was delayed or advanced too much, the fuel may have not burned fully. The O2 sensor acts as a snitch to the ECU by telling it how well the fuel was burned.

Furthermore, the vast majority of modern engines have wideband O2 sensors. Those sensors have much quicker response and wider signal range. This means that the ECU can actually distinguish between the exhaust gases of each individual cylinders as they pass next to the O2 sensor.

The pre-cat (hot) sensors are used to adjust the short term fuel trims which are primarily used for making sure the engine runs right. The post-cat O2 sensors are used to ensure the catalytic converters are working as expected AND also to adjust the long term fuel trims which generally are used for fuel efficiency.

Since this engine is a V6 with two banks of exhaust headers, it stands to reason that there are totally of 4 O2 sensors. Two are pre-cat and two are post-cat.

Hope this makes sense.