Soldering O2 wires, why not?

[scbodnar]

Why do you have to use crimp wire connectors when reusing the old O2 sensor plug? What does the soldering process damage or alter?

Thanks!

Steve

[1schoir]

Why do you have to use crimp wire connectors when reusing the old O2 sensor plug? What does the soldering process damage or alter?

Thanks!

Steve

Steve:

IIRC, soldering the wires changes the resistance values of the wire and thereby affects the 02 sensor readings.

Perhaps one of our more electrically gifted members can explain the theory in more detail.

Regards, Maurice.

Edited March 26, 2008 by 1schoir

[scbodnar]

Maurice,

So the problem is dissimilar metals, like how thermocouple wires work?

I am assuming that the wire crimps must be made of the same material as the actual wires on both sides of the connection? I wonder if they are or it is better to just buy the pre-wired Bosch OEM unit.

Thanks Again!

Steve

[z281974]

Soldering is fine for the O2 wires. From an electrical standpoint there is no reason not to solder, as long as you're capable of performing the task. I've seen instructions from an universal O2 sensor indicating that soldering is ok. From my personal experience, I soldered the replacement O2 sensor in my Mercedes about 5 years ago without problem to date.

Tom

[1schoir]

Maurice,

So the problem is dissimilar metals, like how thermocouple wires work?

I am assuming that the wire crimps must be made of the same material as the actual wires on both sides of the connection? I wonder if they are or it is better to just buy the pre-wired Bosch OEM unit.

Thanks Again!

Steve

Steve:

I had a CEL on so many times, I decided to bite the bullet and buy the pre-wired O2 Sensor.

However, I wouldn't buy the part from Porsche (they don't make the O2 Sensors, Bosch does).

I ended up buying them from AutohausAZ for $136.58 each, no tax and free shipping, about 5 months ago.

Regards, Maurice.

[rsfeller]

I've been soldiering 02 in many german cars for years with boesch generics with no issues, although the newest cars may have a greater tolerance to operate with a given range compared to a 1986 Vanagon!

[pk2]

I've been soldiering 02 in many german cars for years with boesch generics with no issues, although the newest cars may have a greater tolerance to operate with a given range compared to a 1986 Vanagon!

I soldered leads to connectors for a wideband O2 sensor, had some trouble but the engineer who designed it just now assured me the solder was not a problem, he did seem he was touchy about cutting the and splicing leads themselves though. I didn't ask for elaboration as it wasn't an issue in my case.

People do solder thermocouple leads, but the recommended method is to use use silver solder and stager the connections. Takes a torch I guess.

Regards, PK

Edited March 26, 2008 by pk2

[z281974]

I've been soldiering 02 in many german cars for years with boesch generics with no issues, although the newest cars may have a greater tolerance to operate with a given range compared to a 1986 Vanagon!

I soldered leads to connectors for a wideband O2 sensor, had some trouble but the engineer who designed it just now assured me the solder was not a problem, it did seem he was touchy about cutting the and splicing leads themselves though. I didn't ask for elaboration as it wasn't an issue in my case.

People do solder thermocouple leads, bu it's recommended you use use silver and stager the connections.

Regards, PK

Thermocouples generate microvolts per degree C, and as such any extraneous voltage generated from dissimilar wire connections will adversely affect their accuracy. I've never seen thermocouple wires soldered in the 30+ years I've worked in defense and space industries. The O2 sensor produces approx. 700 millivolts nominal - many thousand times more voltage than the thermocouples' microvolts, so microvolt inaccuracies won't affect it. Also, the ECU is looking more for the large transitions in voltage of the O2 sensor (around the stoichiometric air/fuel ratio), rather than an absolute voltage value. Proper soldering technique involves first making a good physical contact between the 2 wires (wrapping the 2 wires together). The solder mostly seals and supports the connection and is not the primary electrical conduction path.

Tom

[1schoir]

Thermocouples generate microvolts per degree C, and as such any extraneous voltage generated from dissimilar wire connections will adversely affect their accuracy. I've never seen thermocouple wires soldered in the 30+ years I've worked in defense and space industries. The O2 sensor produces approx. 700 millivolts nominal - many thousand times more voltage than the thermocouples' microvolts, so microvolt inaccuracies won't affect it. Also, the ECU is looking more for the large transitions in voltage of the O2 sensor (around the stoichiometric air/fuel ratio), rather than an absolute voltage value. Proper soldering technique involves first making a good physical contact between the 2 wires (wrapping the 2 wires together). The solder mostly seals and supports the connection and is not the primary electrical conduction path.

Tom

Tom:

Thanks for taking the time to explain this in detail. Doesn't sound too much like Greek anymore.

If I now understand it correctly, as long as you use proper soldering technique, there will be no effect that the O2 sensors will be able to measure, so there is no problem using O2 sensors that must be soldered.

Regards, Maurice.

[z281974]

Tom:

Thanks for taking the time to explain this in detail. Doesn't sound too much like Greek anymore.

If I now understand it correctly, as long as you use proper soldering technique, there will be no effect that the O2 sensors will be able to measure, so there is no problem using O2 sensors that must be soldered.

Regards, Maurice.

That's correct Maurice, there's nothing magical about soldering O2 sensor wiring. The main reason some universal replacement O2 sensor kits recommend crimping is because no special tools or skills are required.

Regards,

Tom