99 4Runner Oxygen Sensor and Flares

We need an oxygen sensor for our 99 Automatic SR5. The Auto Zone guy said we could buy one there for $375, but it looks like can buy them much cheaper online ($120 - $150). I have not done much with cars beyond changing the oil and air filters, but he said this part is easy to replace. Would you recommend doing it myself? Are there any good websites that could walk me through the process?

Also, how much do flares run, and where could I get some? Not like the flares on a Limited, but the smaller, black plastic ones that seem to be an option on some 4Runners.

Thanks

Some penetrating oil, a special socket (?) and a torque wrench to tighten the new one is all you need. You should probably put some anti-seize compound on the threads of the new one before you install it. Torque to 14 ft-lbs.

The price difference you're seeing is probably the difference between HO2 sensors and Air/Fuel Ratio sensors. A/F Ratio sensors are much more expensive than HO2 sensors.

http://www.autoshop101.com/forms/h37.pdf

Better check with a Toyota parts department to get the part number you need. They are not interchangeable.

You can check the function of HO2 or A/F Ratio sensors with a ohmmeter on terminals B+ and HT (Pair of terminals nearest three-feature side of connector, two furthest from two-feature side). Cold, an HO2 sensor should read 11-16 ohms. A cold A/F Ratio sensor should read 0.8 - 1.4 ohms.

What is a flare? A mud flap?

Go to gadget's website (www.gadgetonline.com), and go to his URD link. He sells the sensors for a lot cheaper than you would find them at the dealer. That's where I'm going to purchase them. He has a pretty good rep. amongst 4Runner owmers.

Thanks for the help with the HO2 sensor. Here is the best example I could find of fender flares. These are more like the bulky ones you see on the Limiteds, but I have also seen smaller black plastic flares on 4Runners and some Toyota Trucks. Anyone know where I can get those?

http://www.rockymountainsusp.com/W_BWACKR_Toy.HTM#Photos

I did a little more research and it seemed like the general consensus for a 99 4Runner with a P0171 code is a MAF sensor that needs to be cleaned. If this doesn't work, then it is the HO2 Sensor Several websites gave instructions on how to clean the MAF sensor (which is fairly easy), so I was in the process of doing this, when we called a local mechanic to ask him a question. He was surprised we were trying to clean the MAF sensor, and told us we should change the air filter instead. None of the websites, forums or automotive books I've read during the past week suggest that as a fix to the P0171 code, so I was very skeptical, but willing to try that before I messed with the MAF sensor. I changed the air filter, and reset the check engine light by pulling the EFI fuse in and out. We've driven in for the past two days, and the light has not come back on yet. I'm kind of surprised and wondered if you have any comments.

Another thing I should mention is that I'm in California, and I believe the 4Runner I own has always been in California (according to the CarFax). Apparently that makes a difference with the emissions mechanics.

The CA 4Runners have A/F ratio sensors.

Thanks Brian R. Now I see where the Auto Zone guy came up with $375; the A/F ratio sensor is much more expensive than the before cat H02 sensor for the same model toyota (I just love CA!!) I took a look at the autoshop101 link you sent me earlier, and it was very helpful in giving me a better understanding of all of this. If the check engine light comes on again, I'll know what to do. Thanks again.

You're welcome.