O2 Sensor vs. air/fuel sensor

[phil123]

O2 Sensor vs. air/fuel ratio sensor

What's the difference between an O2 Sensor and air/fuel ratio sensor?

I started the thread below because the CEL light is on in my 2003 V6. I replaced both front O2s and cleaned the MAF sensor with no luck. So I took it to the dealer this morning and they say I've got 2 bad air/fuel sensors are going to cost me 656 to replace. Just want to be sure I'm not getting jacked around before I pay them to fix it.

http://www.toyota-4runner.org/showthread.php?s=&threadid=22074

 

[OUTRNNR]

Re: O2 Sensor vs. air/fuel ratio sensor

What's the difference between an O2 Sensor and air/fuel ratio sensor?

I started the thread below because the CEL light is on in my 2003 V6. I replaced both front O2s and cleaned the MAF sensor with no luck. So I took it to the dealer this morning and they say I've got 2 bad air/fuel sensors are going to cost me 656 to replace. Just want to be sure I'm not getting jacked around before I pay them to fix it.

http://www.toyota-4runner.org/showthread.php?s=&threadid=22074

If I were you I'd gather more info before paying.

From what I know, which isn't a whole lot, the O2 sensor is in a way the air/fuel sensor. When an engine is running rich it is emitting alot of CO and it will tell the ECU to adjust. Likewise if the engine is running lean it will emit alot of NOx and the O2 sensor picks this up too. Its all part of the emissions system, so if I were you I'd try to determine what exactly they want to replace. I'd get specific part numbers and brands.

 

[toybox]

Sounds to me that the air/fuel sensor is an O2 sensor. Did you tell them that you had already changed two O2 sensors? How many does your truck have? I just did a Mercury and it had 4. 2 on each side of the V6 engine with one pre and one aft of the cat. converter. I would at least ask them to explain or be more specific as to what an "air/fuel sensor" is.

 

[phil123]

I told him I had already replaced the front 2 O2 sensors in our initial conversation. When he called me back to tell me what he had found he said it was the air/fuel ratio sensors and not the O2 sensors. He told me I should take those O2 sensors off once I got it home and try to return them because I didn't need them.

 

[POS Racing]

Re: O2 Sensor vs. air/fuel ratio sensor

So I took it to the dealer this morning and they say I've got 2 bad air/fuel sensors are going to cost me 656 to replace. Just want to be sure I'm not getting jacked around before I pay them to fix it.

http://www.toyota-4runner.org/showthread.php?s=&threadid=22074 [/B]

Sounds like you are getting hosed, ask them to show you the $656.00 parts.

Did you ever do a drive cycle to see if the error cleared on it's own??

 

[phil123]

I did not do through that drive cycle that was posted in my other thread. I have a hard time believing that a dealer service tech is going to go through that whole drive cycle. I did drive it around for quite some time over the weekend and the light did not go off.

 

[toybox]

The dealer needs to be more specific. I searched partznet and couldn't find anything like an air/fuel sensor. I did find the stuff I thought I would find like O2 sensors, EGR and stuff. I would love to know the real name of this part that they changed.

 

[phil123]

I searched some as well and the only place I've found that claims to carry an air/fuel ratio sensor is:

http://replacement.autopartswarehou...RU-V6-006&part=Air Fuel Ratio Sensor&dp=false

The O2 sensor they have is a different part number, so they don't appear to be the same part. I also noticed in the link below that it warns not to use these O2 sensors to replace an air/fuel ratio sensor because it will void your warranty.

http://replacement.autopartswarehou...O&model=4RU-V6-006&part=Oxygen Sensor&dp=true

 

[phil123]

In yet another attempt at making sure I'm not getting the shaft I called a different Atlanta area dealer just to price an air/fuel ratio sensor. He confirmed that he had it in stock and that it is not the same thing as an O2 sensor.

 

[toybox]

In yet another attempt at making sure I'm not getting the shaft I called a different Atlanta area dealer just to price an air/fuel ratio sensor. He confirmed that he had it in stock and that it is not the same thing as an O2 sensor.

How much was it?

Seeing as the Bosch was ~$158 a piece then two of these from Toyota was probably $400-450 just for the parts. I guess it seems like the price you got could be fair considering getting these installed at a dealer. Sucks that you couldn't trouble shoot this yourself and at least save on the install but at least you know they weren't ripping you off.

 

[phil123]

He wanted $210 a piece for them at that other dealer.

 

[phil123]

Well I went and picked it up and 663 bucks later the CEL is off. He replaced the same 2 O2 sensors I replaced except he called them air/fuel ratio sensors. He said only the rear 2 were called O2 sensors. He claimed the computer did not recognize the after market Bosch sensors I installed. What I really suspect is that my aftermarket sensors were fine but there is some additional step to clearing error codes that I was not aware of. These guys love to play on your confusion.

So for future reference the error codes it was throwing were P2238 and P2241. These are your 2 air/fuel ratio sensors in front of the cat. They are easy to replace and would cost you around 200 a piece if you did it yourself. The unknown is how to clear the codes and reset the computer. Every person I talked to told me a different method and none of them worked for me. Hopefully you guys have better luck than I did if you tackle this.

 

[the_bear]

It is possible that the front two sensors are actually wideband O2 sensors, which are much more accurate than typical O2 sensors, and much more expensive as well. I found this article that seems to claim that newer LEV and ULEV vehicles need a wideband for more precise monitoring of air/fuel ratio.

Wideband Article


This would explain why the rear two are "regular" O2 sensors, as they only need to detect catalyst function, rather than a precise ratio.


-Eric

 

[toybox]

Well the fore and aft (of the Cat. Conv.) O2 sensors are different. So if you had rears in the front then I can definitely see it NOT fixing the problem.

 

[greasefingers]

I cannot speak for the v6 but the v8 engine has four identical oxygen sensors. They are not the Wide range type. There is also no P2238 or 2241 codes, so I guess you have discovered another difference about the two engines.

BTW that is so expensive for something that is prone to fail on all vehicles.

 

[toto]

An "air/fuel sensor" is an O2 sensor on a vehicle with California Emissions. I don't know what's different about the sensors - just that if you have CA Emissions, you have A/F sensors.

 

[jims86runner]

A/F SENSOR VS OX SENSOR

BASICALLY DOES PRETTY MUCH THE SAME THING, EXCEPT
A/F SENSOR IS FOR CARS THAT COMPLY TO CALI EMISSIONS
(THEY ALSO HAVE HEATED CIRCUITS)
FIND HARD TO BELIEVE BOTH ARE BAD

 

[mikestang]

Holy shizzle, you paid $700 to have 2 02 sensors changed that you alread changed yourself? That is the biggest rip-off I've ever heard.

After you changed them yourself you should have gone to autozone, used their code scanner and seen what the code was. That would of cost you $0.

 

[phil123]

Yeah, the whole deal was sketchy. I actually did go to Autozone and Advance when I was troubleshooting it. I had them read the codes before replacing them and clear the codes 4 or 5 times after replacing them when I tried various fixes. The CEL light would come back on within seconds, so I finally gave up. The Toyota service manager claims that the computer was not recognizing the Bosch sensors and that he had seen it many times. I'm not sure if I'm buying that, but I couldn't get the light to go off so I didn't really know what else to do. I actually complained about how much they charged me for the parts and got them to refund 100 bucks, which put the repair at about $570. That still seems like a rip off to me, but the sensors were 210 a piece and they claimed 1.5 hours of labor. I'm just writing it off as a typical dealership experience. This was at Mall of Georgia Toyota and they are as slimy as the next place. I've never once felt like I was treated fairly at any dealership so I will continue to avoid them if at all possible.

I was able to return one of the Bosch sensors and could probably return the other one as well if I hadn't thrown out the box. In the end I'm out a little over $600.

 

[el_chapu-bling]

I had a hard time trying to figure out this O2 sensor - A/F Sensor deal myself...

But like someone mentioned it already, for California spec vehicles the O2 Sensor is called the Air-Fuel Ratio Sensor.

I had a CEL a couple of months ago and I had to replace the MAF and the O2 sensor...I simply went to Autozone and bought what they had. The light did not turn on anymore, so I figured everything was fixed.

Then, when I took my 4Runner to the dealer for other work some time later, the diagnostic said that I had a bad A/F Sensor (not covered by the warranty). I had a hard time trying to find one on my own. I didn't know what the part was, where it went and what it was for. I went to various auto parts stores and nothing, they only carried O2 sensors. It appears this part is only sold by Toyota dealers...but since the car was not giving me any problems and no CEL, I left it alone...

Yesterday, I took my car to the Smog station (in California) and it failed the NO (PPM) reading only. The guy said that it may be a bad O2 sensor, but I told him I had already replaced it within the last couple of months. He asked if I had bought it OEM or from an auto parts store. I told him mine was an Autozone O2 Sensor and told me that was the problem.

I did some reading on my own and I found out what I posted above, the O2 Sensor IS indeed the A/F Sensor, but I have to buy it from a Toyota dealer. I called about 6 dealers and the price ranges between $207 and $224 each...

I guess I wasted my money on the first O2 sensor that I bought, since what my 4Runner needed was the A/F sensor that I have to buy now...

I will buy it this week and re-Smog the car. I will post results then.

BTW, I have a 2000 4Runner V6 2WD/SR5 Auto