Oxygen Sensor Replacement

I have a 94 GC with 3.3 engine. Same body style IIRC. When my O2 sensor went, I watched the mechanic replace it.

He reached behind the engine between the engin and the firewall with a pair of wire cutters. He cut the wires from the sensor, and removed the connector & loose wires from the mating connector housing.

He then reached down to the sensor with a socket on the end of an extension (can't remember if there was a universal on it or not), and removed the old sensor.

The new sensor was installed, and torqued in place with a wrench, and then the connector clipped into the system.

Elapsed time to re & re: 5 min. No hoist. Nothing weird. Took him another 5 min to start the van and scope the sensor signal to make sure it was responding properly.

hth

I cannot see any way as to how the mechanic could have been able to do that with the air intake plenum on top almost touching the firewall. There is at most 2 inches of space between the two, and there are vacuum fittings and hoses in that area, but I will take a better look at the space between the engine and the firewall.

~Robert.

I have a 94 T&C with the 3.8 and a 95 T&C with the 3.8 and I can't see how you could torque it into place with a wrench from the top. I've done my own O2 on the 95 and I came up from the bottom, it is easy enough that way and plenty of clearance. I can see how you would get it out with a socket and universal and extension - but only if it broke free right away, if it's like most O2 sensors an extension with a universal would not apply enough torque. But there is not enough clearance from the top to manipulate anything other than a stubby wrench and that would not torque it down enough.

Ted

Here is what I did for my '96 T&C when the sensor needed replacement:

I went to a local garage and paid the guy $150 for the sensor and replacement. Usually, this is the sort of thing I would do myself, but I exercised the wisdom of understanding that it wasn't worth the effort this time.

I'll make it up in something that I can do well. I didn't stick around to see how it was done. Although after reading the previous account of the guy who did it from the front of the engine, I am sorry that I did not.

Ken

That's a pretty easy repair, I think. I wouldn't go to a garage for it.

The physical install looked pretty easy; however, I do not have the diagnostic equipment (simple though it is) to make sure that it was indeed the O2 sensor that was faulty.

These days a shop bill of $150 is pretty low. Given the fact that I was in and out of the shop in less than 30 min (a good 15 of which was what it took them to write up the invoice and process the payment), I would say that the conveinience factor was well worth paying the shop.

The >That's a pretty easy repair, I think. I wouldn't go to a garage for it. >

An inexpensive, under $10, volt meter is all you need to test your O2 sensor.

-------------- Alex

The mechanic used a portable scope to diagnose mine. When he connected it, you could see a solid 50% duty cycle square wave which did not change with changing engine conditions.

Once the O2 sensor was replaced the O2 sensor output was a pure DC voltage whice would hold steady for a given throttle position, but the voltage output would change hen the trottle position changed.

I suppose you could use an analog volt meter to see if the voltage was tracking properly, but a digital voltmeter would be a pain.

Pretty sure I've got an old analog voltmeter around somewhere. I'll remember that next time! Thanks