cheap lambda (O2) sensors at Repco - suitable for general use (including 205 Si)?

[natumbri]

Hi,

I understand that lambda sensors have a finite lifespan (~80,000km?), and that replacing one that has reached the end of its life can help with performance/fuel economy/general running of a motor. In light of the above, in the course of freshening up a 205 Si, I'm going to replace the lambda sensor. I take it a 4-wire lambda sensor is the type required.

Now, the question: prices for lambda sensors seem to range extremely widely but, as I understand it, all 4-wire sensors are pretty much the same, and different part numbers correspond to different plugs (which can be changed without too much difficulty). I see that Repco have a bunch of NTK 4-wire O2 sensors on 'clearance' at the moment for $14-$21 (see first six in pic below - they say not in stock, but if you try various stores, they can be found) - is there any reason why one of these cheap items wouldn't do the job?

Cheers,
Nik

 

[schlitzaugen]

I think the lambda sensor on the GTI has a Bosch connector, not sure about the Si but would guess it is the same. From memory the GTI has two terminals, not four, maybe the Si is different. Either way, I would look for one with a Bosch connector to make life easier.

Also, the wires on the GTI sensor are some other metal, not copper so not possible to solder and difficult to crimp onto. If that is the case with your sensor, I would make a short adaptor cable to go between the sensor and the car wiring rather than try to change the factory connector on the sender.

 

[Matthew]

No adapters or joiners with odd cables on O2 sensors, the differential potentials of the metals in the wires will upset the sensor. There are kits to join that are made for the job for this however the full wiring to join at the connector as is now is preferable. The kit for this as above should be up to the task. Replicate the connection in the car. normally 4 wire these days.

 

[schlitzaugen]

The car wiring is just an adaptor between the sender and the ECU, why would the Lambda sender see any difference if there is another one in line?

 

[Matthew]

Because of metal nobility and the fact that dissimilar metals joined for a junction create their own voltage as the metal oxidises / corrodes that upsets the O2 system. Your call.

 

[PeterT]

Because of metal nobility and the fact that dissimilar metals joined for a junction create their own voltage as the metal oxidises / corrodes that upsets the O2 system. Your call.

Indeed. When you consider the output is 0-1V and centered around approx. 620mV for stoichiometric, it doesn't take much from a metal mismatch to add/subtract to the mixture. Refer to galvanic table.

 

[schlitzaugen]

Because of metal nobility and the fact that dissimilar metals joined for a junction create their own voltage as the metal oxidises / corrodes that upsets the O2 system. Your call.

I understand that, but considering you already have one such connection from factory (which is most likely taken into account) and you don't add another dissimilar metal connection (because at the other end of the adaptor cable you will have similar metals in contact) I don't see the problem.

Either way, the OEM connector in itself is not the problem but the wire to spade crimped connection is.

 

[Jared]

@natumbri did you ever end up replacing the sensor?