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I need to replace the oxy sensor on the ej20tt motor in my outback, a genuine subaru one will cost about $450, which is nuts. Is there any reason I can't just get a $50 generic bosch narrowband sensor and splice it in? The factory one is a 3 wire one, which should be heater, ground and signal.
I figure that the genuine subaru ones are probably rebranded bosch ones anyway...

im running a ngk in my lib now. Plugged strait into the existing wiring, all was perfect. cost me about 100 i think.

alex

tmh983 wrote:I need to replace the oxy sensor on the ej20tt motor in my outback, a genuine subaru one will cost about $450, which is nuts. Is there any reason I can't just get a $50 generic bosch narrowband sensor and splice it in? The factory one is a 3 wire one, which should be heater, ground and signal.
I figure that the genuine subaru ones are probably rebranded bosch ones anyway...

Slightly off-topic but isn't it heater +ve, heater -ve, and signal ? The gorund is through the exhaust/engine/earth cable isn't it. That is why the earlier ones are only 1 wire ??

I don't think they are earthed through the exhaust system, but I could be wrong. The exhaust on my car at least doesn't actually have a solid metal connection to anywhere on the engine/body... its all seperated by gaskets and rubber hangers. So the oxy sensor would definatetly need a separate earth wire.
I think single wire 02 sensors are not heated, and thus only have 1 wire -signal
2 wire sensors have signal and heater, and are earthed through the exhaust
3 wire sensors have signal,heater and heater earth
4 wire sensors have signal, signal earth, heater and heater earth
I think thats generally how they are wired.

Anyway, I found the bosch part number for the genuine subaru oxy sensor and ordered it from a uk website for about 1/4 the price of a 'genuine subaru' one.

tmh983 wrote: Anyway, I found the bosch part number for the genuine subaru oxy sensor and ordered it from a uk website for about 1/4 the price of a 'genuine subaru' one.

So post up a link - I need a o2 sensor as well

tmh983 wrote:I don't think they are earthed through the exhaust system, but I could be wrong. The exhaust on my car at least doesn't actually have a solid metal connection to anywhere on the engine/body... its all seperated by gaskets and rubber hangers. So the oxy sensor would definatetly need a separate earth wire.
I think single wire 02 sensors are not heated, and thus only have 1 wire -signal
2 wire sensors have signal and heater, and are earthed through the exhaust
3 wire sensors have signal,heater and heater earth
4 wire sensors have signal, signal earth, heater and heater earth
I think thats generally how they are wired.

My 3 wire sensor has one wire with a black stripe and 2 plain white wires. So I would imagine that the 2 white wires are for the heater - other wise they wouldn't be the same colour ??

Try here: http://www.cyberspaceautoparts.com.au/c ... nsors.html

This is the one i ordered: http://www.worldcarparts.co.uk/CarParts ... fault.aspx

It is the correct type of sensor, the only difference may be the cable may not be long enough, but i'm happy to splice some extra wire to save myself $350!!

I've just got a new o2 sensor for my EJ. My local parts store had a generic sensor that you wire the plug into the loom. I asked for a subaru plug and play replacement (generic brand, I know it wasn't a bosch or the like), same price but a day's wait to order it in.

5 minutes of my time and my o2 sensor is replaced. Will be keen to see if my fuel consumption changes

Cheers

Bennie

tmh983 wrote:I think single wire 02 sensors are not heated, and thus only have 1 wire -signal
2 wire sensors have signal and heater, and are earthed through the exhaust
3 wire sensors have signal,heater and heater earth
4 wire sensors have signal, signal earth, heater and heater earth
I think thats generally how they are wired.

Not quite

1 wire sensor is as you said, just a signal wire and is grounded though the exhaust pipe

2 wire sensor is not heated. The 2 wires are signal and signal ground

3 wire sensor is heated. 2 wires are for the heater, the 3rd wire is the signal and the signal ground is through the exhaust pipe.

4 wire sensors are as you said.


Hope that clears it up

tmh983 wrote:I don't think they are earthed through the exhaust system, but I could be wrong. The exhaust on my car at least doesn't actually have a solid metal connection to anywhere on the engine/body... its all seperated by gaskets and rubber hangers. So the oxy sensor would definatetly need a separate earth wire.
I think single wire 02 sensors are not heated, and thus only have 1 wire -signal
2 wire sensors have signal and heater, and are earthed through the exhaust
3 wire sensors have signal,heater and heater earth
4 wire sensors have signal, signal earth, heater and heater earth
I think thats generally how they are wired.

Anyway, I found the bosch part number for the genuine subaru oxy sensor and ordered it from a uk website for about 1/4 the price of a 'genuine subaru' one.

So there are no bolts holding your exhaust together at the joints or the manifold to the block? must be those magic sticky gaskets

d_generate wrote:So there are no bolts holding your exhaust together at the joints or the manifold to the block? must be those magic sticky gaskets

yeah ok, fair point.

Anyway, the oxy sensor I ordered arrived today, as expected the sensor itself is identical, just a different connector on the end of the wires. Took 5 minutes to cut and shut the old plug onto the new sensor wires.
Fuel economy dropped from 12-13 L/100k (rooted oxy sensor) to 8 - 9L/100 on the 150km test drive I did today. Idle is much much much more smooth, engine seems to run smoother in general.
Win.
Very pleased with the World Car Parts, will definately use them again.

So how did you test it to know it was knackered? I'm pretty sure I need 2 as the economy in the WRX is atrocious, has been since I put it together & shoved an old oxy sensor I found laying around in it and my Lib has somehow lost about 80kl per tank over the last couple of tanks.

I knew it was buggered cos I snapped it in half lifting the new engine into place.
I'm not sure of the best way to you could test the sensor in your car. If you can hook a multimeter into the signal wire without disconnecting the sensor, you should see the voltage flicking back and forth between 0.1 - 0.9 volts when the car is cruising steady.
Or if you can get your hands on a wideband sensor, that will tell you if it is maintaining 14.7 at cruise.
The ecu should spit error codes if they oxy sensor is really buggered like mine. If the sensor is just slow to respond then I don't know if the ecu will throw codes.