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Discussion Starter #1
Hi,

I need to replace rear lambda sensor on my Alfa 147 1.6, '01, 105hp.

Since I plan to do it myself I did a research and it seems that the sensor is Bosch - 0258006375

However there is a Bosch universal replacement 0258986615 which seems to be cheaper.

My question is: is there any problem to fit the universal one and will it work as the direct fit. I have heard that the only difference is the plug (the universal one does not have a plug so I will have to connect each one of the four wires)

My current rear sensor is not Bosch and I get an error code and Motor Control System failure message. I believe this is because of the different heater resistance.

Any comments would be greatly appreciated.
 

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From bitter experience, if you are changing a lambda sensor for diagnostic reasons, always use an OE quality part, better still, the OEM and never, ever a universal one. That won't fix your problem.

Why exactly do you need the rear one changed anyway? It sounds like you are doing a bit of guesswork.
 

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Discussion Starter #3
Why exactly do you need the rear one changed anyway? It sounds like you are doing a bit of guesswork.
This is what the diagnostics shows. Apart from that as I mentioned i get error code and Motor Control System failure message.
 

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I hoped you had the exact error code description. I say that because if it is a signal error, the rear sensor wave form should be a flat line anyway. If it is voltage variation which is the problem, and that can be a front sensor switching slowly or even the efficiency of the cat which is the real problem.
 

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I hoped you had the exact error code description. I say that because if it is a signal error, the rear sensor wave form should be a flat line anyway. If it is voltage variation which is the problem, and that can be a front sensor switching slowly or even the efficiency of the cat which is the real problem.
I will get the error codes by the end of the week.
The front lambda is working fine - the wave is ok. However I had a damage on the cat and I had to remove it. Now the cat pipe is actually empty. Do you think this may cause motor control system failure message? I have read somewhere in the forum that this situation does not cause any problems except maybe for MOT. Apart from that I think the codes were related to lambda sensor.

I will look for your help again when I get the error codes.
 

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I will get the error codes by the end of the week.
The front lambda is working fine - the wave is ok. However I had a damage on the cat and I had to remove it. Now the cat pipe is actually empty. Do you think this may cause motor control system failure message? I have read somewhere in the forum that this situation does not cause any problems except maybe for MOT. Apart from that I think the codes were related to lambda sensor.

I will look for your help again when I get the error codes.
Haha. It's your cat which is the problem. The rear lambda sensor should be giving a flat-line signal of approximately 1 volt (I think that is the value). Because the cat element is not there it is only mimicking the readings of the pre-cat sensors because there is no more converting happening to the gases by the time thy reach the rear sensor.

That being the case, a new sensor will not solve your problem. A new catatytic converrter will. However, there is a cheaper way, I believe. I've not seen this, but I believe that on the aftermarket, you should be able to buy a resistor instead of the sensor. This will have the correct resistance values to provide a constant return voltage of the correct value so as not to trip a code in the management system. A supplier of exhausts that do rear cat replacement boxes should understand this.
 

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Haha. It's your cat which is the problem. The rear lambda sensor should be giving a flat-line signal of approximately 1 volt (I think that is the value). Because the cat element is not there it is only mimicking the readings of the pre-cat sensors because there is no more converting happening to the gases by the time thy reach the rear sensor.

That being the case, a new sensor will not solve your problem. A new catatytic converrter will. However, there is a cheaper way, I believe. I've not seen this, but I believe that on the aftermarket, you should be able to buy a resistor instead of the sensor. This will have the correct resistance values to provide a constant return voltage of the correct value so as not to trip a code in the management system. A supplier of exhausts that do rear cat replacement boxes should understand this.
Thank you very much. This was very helpful.

DO you mean that I will have to remove the lambda sensor and just put a resistor or something on the plug that leads to the ecu?
 
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