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Discussion Starter · #1 ·
I'm about to replace a genuine Bosch O2 sensor in my 2.1 c900 that was fitted new (genuine Saab oldstock 93 92 672) last August but has now failed (less that a year since installing). Refer to my recent thread about odd fault codes.

Luckily I have one more of the same.

So I'm attempting to work out the scope for Bosch O2 sensors equivalent to the Saab 93 92 762 oem part. The Bosch 13957 part gets reported as equivalent via many of the search results though the mpn seems to be different - Saab OEM is 0 258 003 028 while I'm seeing 0 258 003 957 and some others shown. For our purposes are these all functionally identical?

C900's with B202/B212 and 9k's with B202 appear to use the same O2 sensor.

But there are none in stock anywhere in Australia (of the genuine Bosch kind). Some other cars of the same era use O2 sensors with the same connector arrangement.

For those with the Lucas system, can they use the Bosch o2 sensor. Is the Lucas O2 sensor usable with the Bosch system?
 

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There are only two types of narrow band O2 sensors from Bosch... thimble and planar. The only difference between all the bazillion part numbers are the sensor type, the connector type, and whether it's heated or not. The dimensions and threads are all, AFAIK, the same. You can generally tell the difference between a planar and thimble sensor by the probe - the correct thimble sensor will have a "slot" on the side like this:


Find a heated thimble sensor, put the right connector on it, and have a ball. :)

Planar sensors didn't come about until the mid/late '90s.

IDK what Lucas used, but probably a regular old Bosch O2 sensor.

Any '80s European car and probably any '80s Ford or GM will have the right sensor, although Ford and GM were late adding heaters.
 

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Siegfried says CU14 uses a titania O2 sensor. Bosch's are zirconia. They work differently, and are not compatible.
 

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Craig are you saying you can get Lucas easily ? I would of thought them rarer here , AFAIK lucas was only on very late Turbo 900's in Oz .
Have you meaured the sensor ? sure its the failure ? Its unusual ( well in my experience it is )
 

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I will also throw this on the fire:

Bosch sold three type of thimble sensors:

1. Unheated 1-wire
2. Heated 3-wire
3. Heated 4-wire

c900 has no monitoring of the heater circuit - so you can technically go either way. Heated sensors perform better, so ideally you want a heated sensor. Even on an 8v car which didn't come with one from the factory - you just need a little <5a circuit to run a heater.

The difference between 4-wire and other sensors is 4-wire circuits have a dedicated ground for the output signal, which leads to more accurate results. On 1- and 3-wire sensors the signal uses the engine itself as a ground. On Ford EEC systems (based heavily on Jetronic), Ford ran a ground from the EEC ECM to the exhaust manifold to improve results. Bosch later added a 4th wire to the sensor to take the sensor back the ECM, as we see in Motronic and even Trionic.

You can use a 4-wire sensor on on a c900. You could just ground the sensor to the exhaust or engine, or you might net some improved sensor performance by bringing the ground to the ECM or even the ground point on the top of the head. I've always meant to try this, but never have. On other cars, retrofitting a 4-wire sensor is often beneficial. You cannot leave the 4th wire floating. It must be grounded.

The newer planar-style sensor uses less power, switches faster, and provides more accurate readings. On modern fuel injection, you cannot switch the two because the ECMs are calibrated to the specific performance of the sensor type (you can see my misadventures on that subject!). Older fuel injection systems aren't so sensitive. I run a planar-style sensor on my XR4Ti running EEC and it's been fine. I suspect you could run a a planar sensor on a c900 and it would be fine too. But I've not tried it. All planar-type sensors are 4-wire AFAIK. They are visually different than thimble-style sensors.

Planar and Thimble sensors are DIFFERENT than "wide-band" or AFR sensors. They are not the same. Most AFR sensors are 5-wire, but I feel like there are some 4-wire sensors out there. AFR sensors look similar to planar sensors as they are based on the same technology; they look different than thimble sensors.

Any Bosch sensor for a car made before 1994 will be a thimble sensor as '94 was the year planar sensors were introduced. :) Very few cars got planar sensors until the late '90s, so most cars through the '90s will still use thimble sensors. T5 cars, for example, are thimble-style. T7, I believe, are planar.
 

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Discussion Starter · #8 ·
Ok so there's a bit of scope. I didn't know any of the technical aspects about 02 sensors so that's all really good info. For lack of availability of genuine Bosch sensors, are any aftermarket ones worthy of considering or should only the genuine ones be used?
 
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