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Whiskey makes me Frisky
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Discussion Starter #1
So I think both of my o2 sensors are bad. When I put my car in for a cat replacement ( or should I say a stupid california duel cat mid pipe, thank you very much classic mazda douche bags, at least it was under warranty and free) they said that my CEL might be caused by a bad o2 sensor not just the cat. SO my question is whats the life span of an o2 sensor. I have 83XXX on the car as of now. Before you ask I did test them and they do appear to be toast, but thought I'd get another opinion. before I spend $80+ each.

Any recomendations on sensors either would be swell.
 

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Firstly, many cars made after 1996 have more than one cat. The 02-06 WRX has three, one pre turbo and two post. The MR2 Spyder has three and it has less than six feet of exhaust plumbing from it's head to it's tailpipe. It's all in the name of lower emissions. Actually, I can't think of a mass produced car that doesn't have two or more cats right now.

Now, go check Autozone.com for your O2 sensors, they sell Bosch sensors that are a lot cheaper than the factory sensor. I've used nothing but Bosch sensors in my Miata since I got it. I used to burn one a year up, but that's because I had a head gasket leaking coolant into cyliner 4. Now they get burned up because I run turbo with a vent to atmosphere blow off valve. That causes me to run rich between shifts and eventually the O2 sensor just gives up the goat.
 

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Skinny,

Last fall I replaced my narrowband with a bosch. Didn't have it in the car long since I replaced with a wideband. The dealer cost was going to be about $170, so I ebayed and got a bosch universal for about $25. It came with the harness cut off so that I had to splice 4 wires into the stock harness. Worked fine while it was in.

The bosch universal did not have "bosch" engraved on it, but had a Ford part number, and the bosch symbol, obviously an OE part.

The full service manual (for a 95) says that the resistance of the heater element should be 13 ohms. The stock sensor was about 13.3 ohms and the universal was about 9 ohms. Not sure if this would throw a code (I'm using a standalone ems), don't think so but maybe someone else knows better. I think you throw a code if the heating element doesn't work which would show infinite resistance.

My stock o2 sensor had about 105k miles on it and was still working. A life of NA, no FI, but lots of auto-x and some track use. A long hard life for the o2 sensor. If you do have a failed sensor I would guess it is the one closest to the head.

-Just checked my modified narrowband (stock harness on bosch universal) and the harness in the 95 is exactly the same as both harnesses on the 99 motor (got a 99 motor sitting the garage), with the exception of the color of the plug inside the harness. But it plugs right in.

Bruce
 

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Skinny,

Here is more info on that bosch universal I got off ebay. I copied this info from another one of my posts:

The numbers on the side of the sensor:

Ford 6E10
4L3A-9G444-AA 685108 00
0 258 006 562 982/ A .
(bosch symbol) 12V

Hope this helps.

Bruce
 

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Whiskey makes me Frisky
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4,545 Posts
Discussion Starter #6
Anyone know how to test an o2 sensor?

When I was testing both of mine today, one pin (blue wire) was showing it was dead while the other (white wire) was showing it as being fine. then I have the other two black wires.

I have both a multimeter and a sensor tester.
 

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Skinny,

There are 2 tests for the o2 sensor, one is for the sensor and the other for the heater element.

To test the sensor itself:

1. Warm up the engine to normal operating temperature and run it at idle.
2. Disconnect the heated oxygen sensor connector.
3. Measure the voltage at terminal A.

Spec:
engine condition: (at terminal A)
Idle (v): below 1.0
increasing engine speed (v): 0.5- 1.0
decreasing engine speed (v): 0 - 0.4

4. If not as specified, check the intake air system, the fuel system and run the on-board diagnosis test.
5. If these systems are OK, replace the heated oxygen sensor.

Heater

1. Disconnect the heated oxygen sensor connector.
2. Measure the resistance between terminals C and D.

Resistance : Approx 13 ohms [20 C {68 F}]

3. Replace the heated oxygen sensor if not as specified.

The terminal map on the harness looks like this:

A C
B D

There are a couple of guides that guide the harness properly into the plug. The guides are next to the A and C terminals.

If you need to replace the sensor, the tightening torque is 22-36 ft-lbs. Use some antisieze on the threads, but keep it the antisieze off the sensor.

Bruce
 

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Whiskey makes me Frisky
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Discussion Starter #10
Okay, well trying to tackle getting the fockers off now. the one on the midpipe doesnt seem hard if I can budge it, but how the hell do you get this one off? there is no room for a spanner length and the width of the head(as it hits the bottom of the header) and even if I could get one on, there is no room to swing it up or down as the wheel well gets in the way.

Any ideas.

its 22mm for the sensor right??



 

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Skinny,

I've never had to use one (yet, haven't started taking apart the 99 motor), so I'm not posative that it will work in this case, but there is a socket that you can get at some autoparts stores that is designed to fit over the sensor. It has a slot in it to allow you to put the socket on the sensor over the wires.

I hope this link works:

http://www.autozone.com/R,NONAPP24171/store,/shopping/accessoryProductDetail.htm

I notice that the sensor is recessed into the header, this tool may help.

Bruce[/url]
 

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Whiskey makes me Frisky
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Discussion Starter #12
Sweet thanks Bruce.

I'll see what I can get, been to autozone numerous times this week and havent found anything useful so am going to sears this afternoon and let you know whats easiest for when you do pull apart your 99
 

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Whiskey makes me Frisky
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Discussion Starter #13
Quick update if anyone cares.

The oxygen sensor socket works wonders (thank you Bruce for your knowledge on that), the o2 sensor from the header is now off and replaced, the one that I thought would be the easiest i.e. sitting on the mid pipe has turned into the bigest pain. Attacking it from the top, side or underneath this bastard has turned into my nemesis!

The problem lies with the new cat that I wrote about earlier, when the boys at classic mazda on 2075 north semoran blvd. orlando replaced it "fixing" the problem with my check engine light they neglected to put any antisieze compound on ( or over torqueing it either way they screwed up) when installing the original o2 sensor, well that was the end of december and now its april the CEL is still on and that SOB sensor is tighter then a virgin school girl.

I vowed to never go back after three shite visits, but will attempt one more tomorrow morning after work to see if they will remidy what they have seemed to mess up.

Okay, rant over. continue on.
 
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