Any special trick to replacing an 02 Sensor?

[IdahoMauleMan]

Friends,

The O2 light on my 1986 560SL is staying on, so I picked up a new one and plan to replace it.

Any special trick here, that I should be aware of? Is it pretty straightforward?

[cullennewsom]

Don't touch the sensor element, and don't use or allow any contact with silicone.

[97 SL320]

With many cars from that era (MB or not ) , the O2 light is triggered by mileage not a sensor failure. Follow the speedo cable from the trans to the speedo head. Somewhere along the way there might be a 3" square box with a couple of wires coming out of it. There should be a reset button that when pressed releases the switch.

If a box isn't inline with the cable, look for a 2nd cable coming from the speedo head / switch built into the speedo head.

The actual sensing element is protected by a metal grid so no worries about touching the end of the sensor.

[rowdie]

Originally Posted by 97 SL320

With many cars from that era (MB or not ) , the O2 light is triggered by mileage not a sensor failure. Follow the speedo cable from the trans to the speedo head. Somewhere along the way there might be a 3" square box with a couple of wires coming out of it. There should be a reset button that when pressed releases the switch.

If a box isn't inline with the cable, look for a 2nd cable coming from the speedo head / switch built into the speedo head.

The actual sensing element is protected by a metal grid so no worries about touching the end of the sensor.

No cable on the 560SL. Electric speedo. ODO/trip is gear driven by an elec. motor. I think there is a sensor in the head unit that trips as described. Recommendation is to remove the bulb. There is no reset.
Getting the damn thing out of the exhaust is the major hurdle. I cut the wires and used a 7/8" box end with BFH . PB Blaster, or other penetrating solvent also helps.

[Jack M]

Ahh!
If you not going to replace the 02 sensor, and before I would take the cluster out to remove the bulb, lets do it with a piece of black electrical tape.

Only because if you really do decide later to replace the sensor, then you won't have to take the cluster out again.

[rowdie]

I think he is going to replace the O2 sensor. Replacing it will not turn off the light and AFAIK there is no reset switch or button.

[IdahoMauleMan]

Originally Posted by rowdie

I think he is going to replace the O2 sensor. Replacing it will not turn off the light and AFAIK there is no reset switch or button.

I'm going to give it a go.

FWIW, the light eventually goes off. But I don't think any of the major fuel system, starting and/or idling components have ever been replaced. I figured, what the hell.

[abiby]

Originally Posted by rowdie

No cable on the 560SL. Electric speedo. ODO/trip is gear driven by an elec. motor. I think there is a sensor in the head unit that trips as described. Recommendation is to remove the bulb. There is no reset.
Getting the damn thing out of the exhaust is the major hurdle. I cut the wires and used a 7/8" box end with BFH . PB Blaster, or other penetrating solvent also helps.

Rowdie's correct in that you'll need to remove the bulb. However, if it's original to the car, the O2 sensor is probably due for replacement.

IIRC that's the same way it worked on my '87 Ford pickup and eventually the bulb went out on its own.

[IdahoMauleMan]

Originally Posted by abiby

Rowdie's correct in that you'll need to remove the bulb. However, if it's original to the car, the O2 sensor is probably due for replacement.

IIRC that's the same way it worked on my '87 Ford pickup and eventually the bulb went out on its own.

Thanks.

I forgot to ask, what do the abbreviations in rowdie's post mean, anyway?

[abiby]

Originally Posted by IdahoMauleMan

Thanks.

I forgot to ask, what do the abbreviations in rowdie's post mean, anyway?

afaik - as far as I know
iirc - if i remember correctly

[meltedpanda]

there is a special O2 socket wrench you can get , allows use with the wires