shaxs

Hey Everyone,

I have a 1999 4Runner with 201,000 miles on it. We love this 4Runner. So much in fact that we are planning to buy a Gen 4 in a year or so. So here is the deal. I moved to Texas from California. So, I assume I still have to get a California o2 sensor correct? I can't change it out since the computer is calibrated for a Ca o2 sensor? Anyways, my real question is what sensor should I get? The part stores want $160 for a sensor. I looked at Rock Auto and I see a wide range of prices. I just need this car to last another good year or so. I would prefer a direct fit (no universal). I need the following:

Upstream Direct Fit CA 2 Wheel Drive o2 sensor.

I know you guys recommend the Denso, but given my needs for the time being, would a cheaper Bosch work okay for the next year? We will probably put less than 10k more miles on it. Where and what should I buy? Do I also need to get the oxygen sensor gasket while I am at it?

scuba

Buy a denso. And a denso only.

http://www.urdusa.com/index.php?cPat...bad3rbihp3jkq1

brian2sun

If you have 2 cats, it's CA emmisions and you need to buy the CA O2 sensor. At some point (I think it was during '99) all 3rd gens became CA emmisions. You may have an A/F meter as opposed to an O2 sensor in the front. Maybe give the dealer a call and have them look up your VIN to make sure. Sparkplugs.com has good prices on Denso sensors too.

TheDurk

If the car was born a Cali., it stays a Cali forever and, by Federal law, must meet those standards in whatever State it was sold in or ends up in. The two Cat Cali. system, which became 50-state Federal in 2001 when Cali. only went away, uses an Air/Fuel sensor in the front--no doubt or any need to check VIN. If you have a '99 V6 and it says California emissions on the ID plate under the hood, the front (A/F) sensor is a Denso 234-9002 for an auto trans and 234-9003 for the 5spd.. Use anything else at your own risk. I believe Amazon has the best prices these days, a little over $100. The A/F is a totally different technology and just not compatible with standard O2 sensors, you might just as well screw in a light bulb (if you could) for all the use it would be.

The Denso comes with the gasket, not sure about any others. You may need new stainless nuts, but since you are not from the salt belt, you may be able to reuse the old ones.

shaxs

Thanks everyone. When I get home from work I will take a look and report back. Should I also post the check engine light error code?

eddieleephd

yes as you said before everyone here always says DENSO however Bosch will work and is like 90.00 at AZone

shaxs

Okay Here is the VIN: http://www.decodethis.com/Default.as...GN86R8X00929XX

It does have the California tag under the hood. Guess I will get the oem Denso

BigBallsMcFalls

that is the best, '1 stop, it is fixed' method.

get the 2 stainless nuts and gasket along with it. done and done.

shaxs

So, I also have to shell out a decent amount of money for parts on my 64 Falcon this month. How long can I get with the o2 sensor not working and what are the dangers/damages involved?

TheDurk

You really need to know the codes being thrown. It is very common for an O2 issue to generate multiple codes, The sensor can fail in various ways, e.g. burnt heater, open/short sensor circuit, out of range readings at times but basically ok, etc. In most cases you will force the ECU to remain in open loop (start-up mode) where the ECU ignores the sensor. This will reduce performance and economy dramatically as the ECU has to guess at the best fuel mix and timing without feedback. A decent reader/scanner will tell you if you are in open or closed loop.

The worse case is where you allow large amounts of unburnt fuel to reach the cat. Throwing a rich code at the same time means you are doing this. You will reduce cat life or even destroy it by allowing that to go on. You can leave a p0420 forever (rear sensor only sets codes), but a P1135 carries real risks.

shaxs

I had it but lost it. I will run by today and have it re-checked at Auto Zone.

BigBallsMcFalls

is this the after-cat sensor ? run all you want, no damage. will not pass emission inspection no damage otherwise

is this the before-cat sensor ? could severely damage engine from running too lean and burn out valves...or could damage engine from running too rich and clog you up with carbon deposits and clog the cat eventually. must replace this one when it fails -always-

Fink

Will a Bosch work? Yes.
Will it cause crappy gas mileage and poor performance? Yes.

You're talking a difference of $40-$50, just do it right from the beginning instead of having to spend another $130 or so on top of the $90 you're going to spend on the Bosch now.

TheDurk is right, if you have a California emissions vehicle then you DO for a FACT have an A/F sensor in the front and an O2 in the back.
I went through this whole thing with my '99 - I ended up ditching one cat and putting in a rear O2 sensor simulator from URD, however, we didn't have vehicle inspections where I was living so it didn't matter.

Fink

shaxs

Well, I am pretty sure it is the before cat sensor. I am getting error code P0171. I have cleaned the MAF sensor. I doubt it is a "large vacuum leak" as the probable causes paper points out. If so the truck would run like crap right? I guess it *could* be low fuel pressure.

shaxs

But in my experience, this has usually been the front O2 sensor.

TheDurk

P0171 is "System Too Lean" I believe this means the ECM is running in Closed Loop but the Fuel Trim required is out of range on the RICH side for both short and long-term trim settings. Basically, The ECM is telling you it doesn't believe the readings it is getting from the A/F sensor. If your front sensor has 70K+, best change it first as it is due soon anyway. Detail: P0171 can also get set if you run out of gas. Presumably this is not your case.

In any case, your truck could be running either RICH or LEAN, depending on whether the problem is the sensor itself or elsewhere. Either one can damage your engine or cat. This is not a case to ignore.

shaxs

No we did not run out of gas. I have consistently have gotten this over the years and seems to always be an o2 sensor. I will replace the o2 first and then the MAF if needed.

phildelfino

this is what i did, but i went to

www.rockauto.com

shaxs

Bought a Denso from Amazon for $107 shipped.

shaxs

So I got around to installing the o2 sensor today. It was simple. I drove around for 45 minutes to do errands and everything seemed fine. I then left the battery unhooked for 30 minutes to clear the CEL code. I started the car up and while in park and gave it some gas. The car now stutters for a second. I took it out for a short drive and from a full stop and giving it gas, the car stutters just a tad then goes and seems to be fine. Any clue what the heck I did?