94 camry oxygen sensor question - Toyota Nation Forum : Toyota Car and Truck Forums

bronzemaxell · 10-06-2009, 07:56 AM

my 94 camry, V6 LE, federal emission, there are three oxygen sensor, two before CAT, one after CAT, are they interchangable? like putting the one before cat to the one after cat?
the physical difference i saw was the wire weather proof insulation and an extra boot on the one after the cat.

***Eye8Pussies*** · 10-06-2009, 04:20 PM

no

the two pre-cat ones are interchangable- but have different wire lengths (if oem) if I remember correctly, but the post-cat o2 sensor serves a different function and operates differently

TOY_DataSeek · 10-07-2009, 07:10 AM

Check engine light has been on for a year on mine... How involved is it to replace a bad O2 sensor or is this one for the mechanic? Seems to run just fine though... Thanks

bronzemaxell · 10-07-2009, 07:54 AM

it take a 7/8" wrench or socket with a slit design for oxygen sensor removal. there is few factor influence the degree the difficulty, if it is in front, easier access and to work with, rear and buttom of the car is pain, also if the car is old, and the oxygen sensor may fused to the exhaust. if you already tried and it would not come loose, better approach is take it to mechanic who has a high power torch, heat up then loose, it may avoid rounding the bolt, and save a lot of headache.

TOY_DataSeek · 10-07-2009, 08:34 AM

Thanks for the help. Also, when the dealer told me the O2 sensor was bad, he didn't indicate which one, since I told him the price quoted was too high and the car was running fine. I do need to get that engine light to turn off so I should probably try to get it fixed. What is the best way to diagnose which sensor is defective? Will an auto parts store run a free check and be able to tell me which one is defective or is there a better way? Thanks again for the help.

***Eye8Pussies*** · 10-07-2009, 09:51 AM

autozone will usually run a check for you to see what the code is, and it will tell you which sensor has gone bad

as for taking it off yourself- if it seems to be fused on, run the car and let the exhaust heat up. Wait until the exhaust cools down- almost fully cool, and then take it off with an o2 socket and breaker bar. The headers can definite be done this way, but the post-cat o2 sensor is a bit harder since you usually need quite a bit of leverage to get it off and the hangers for the mid-pipe allow too much flex to really get it off if it's rusted on badly

toyotarocksman · 02-23-2010, 02:56 AM

I have a 94 Camry V6 with the same problem. I took it to the dealer and they ran the code as the oxygen sensor. Didn't tell me which one. I tried to diagnose the problem myself via the instructions from Haynes and it didn't work, AT ALL. Not knowing which one is bad, and observing absolutely nothing wrong with the way the car runs, I've been reluctant to do anything about the Check Engine light. So time has passed, and I've noticed something. It seems that the light coming on is related to how much fuel is in my tank. A full tank of gas, and the light stays on. Under a half tank, and the light goes out. If this is the oxygen sensor (and that might make sense, because the light started coming on after using a fuel system cleaner that guaranteed it wouldn't harm my oxygen sensor lol), then why does it seem to exhibit behavior correlated to the amount of fuel in the tank?

The service guy at the dealer told me my fuel system was dirty (as the cause of my failed oxygen sensor) and offered to clean it for several hundred dollars. Which was BS at any price, because this car's fuel system isn't dirty at all. If anything it's the cleanest, most well maintained 94 Camry on the road with about 55,000 gentle miles on it.

Also, did you replace your sensor? What has happened to your car the last few months? How can I test to find out which oxygen sensor is bad? Something from the panel? Multimeter tests? Do these things just get dirty and function with a cleaning? Why/how did Gunk fuel system cleaner harm my oxygen sensor? Thanks!

hill8570 · 02-23-2010, 10:22 AM

Quote:

Originally Posted by toyotarocksman

I have a 94 Camry V6 with the same problem. I took it to the dealer and they ran the code as the oxygen sensor. Didn't tell me which one. I tried to diagnose the problem myself via the instructions from Haynes and it didn't work, AT ALL. Not knowing which one is bad, and observing absolutely nothing wrong with the way the car runs, I've been reluctant to do anything about the Check Engine light. So time has passed, and I've noticed something. It seems that the light coming on is related to how much fuel is in my tank. A full tank of gas, and the light stays on. Under a half tank, and the light goes out. If this is the oxygen sensor (and that might make sense, because the light started coming on after using a fuel system cleaner that guaranteed it wouldn't harm my oxygen sensor lol), then why does it seem to exhibit behavior correlated to the amount of fuel in the tank?

The service guy at the dealer told me my fuel system was dirty (as the cause of my failed oxygen sensor) and offered to clean it for several hundred dollars. Which was BS at any price, because this car's fuel system isn't dirty at all. If anything it's the cleanest, most well maintained 94 Camry on the road with about 55,000 gentle miles on it.

Also, did you replace your sensor? What has happened to your car the last few months? How can I test to find out which oxygen sensor is bad? Something from the panel? Multimeter tests? Do these things just get dirty and function with a cleaning? Why/how did Gunk fuel system cleaner harm my oxygen sensor? Thanks!

A CEL that correlates with fuel level is more likely gas cap or another component of the EVAP system...real unlikely to be the O2 sensor. If you've never changed your gas cap, I recommend hitting the dealer for a new cap -- they're cheap. Don't do the parts store for that -- part store gas caps are a crapshoot. If that fixes the problem, cool, if not, you needed a new cap anyhow.

Do you know if your rig is a 1MZ or 3VZ engine? I think it would be a 1MZ, which is OBD-II, so you'd either want to buy a code reader or find a parts shops (Autozone, O'Reilly's, Pep Boys, etc.) who will read the code for you. The OBD connector is a bit hidden -- you have to pull the coin box drawer (to the left of the steering wheel), and it's the big D-shaped connector in there.

ShawnD93Toy · 02-23-2010, 10:39 AM

the 94 v6 should be a 1mz. I just ordered two new o2 sensors for my 3vz should be fun replacing them lol

csaxon · 02-23-2010, 12:54 PM

csaxon · 02-23-2010, 12:54 PM

***fenixus*** · 03-02-2010, 03:15 PM

i'm about to replace my rear o2 sensor as well, it seems very awkward as per its voltage range at certain conditions. my current fuel trims (obd2) are sky high, long-term fuel trim at +22% - still not enough for ECU to pop up the CEL (it needs a total of over 38% of both short and long fuel trims adjustment for error code).

which oxygen sensor socket did you use to remove the rear sensor ? i'm at 70k miles here and wondering if i can do it myself (with a help of wd-40 and big ratchet).

i was wondering if this o2 socket does the trick (6-point offset) ?
http://www.harborfreight.com/cpi/cta...emnumber=97177

thanks for answer.

csaxon · 03-02-2010, 04:35 PM

It should work fine. Pb Blaster, Liquid wrench, Kroil oil are better than wd40 for heavy rust busting. If you warm the engine up (exhaust pipe) it will come out very easily.

***fenixus*** · 03-02-2010, 05:13 PM

Quote:

Originally Posted by csaxon

It should work fine. Pb Blaster, Liquid wrench, Kroil oil are better than wd40 for heavy rust busting. If you warm the engine up (exhaust pipe) it will come out very easily.

thanks!

***JohnGD*** · 03-02-2010, 08:14 PM

+1 for warm exhaust pipe. The new sensor should also have some antiseize applied to the threads along with a plastic protective cap on it. NTK is part of the NGK group. Should be a good sensor.

I think the HF style sensor wrench you showed was exactly what I used. It's a very compact one and inexpensive too.