o2 sensor bad?

Question

I have a '96 Plymouth Voyager SE with the 3.0L engine. It is just about to roll to 80K miles.

Symptom--> Start engine again after it has been sitting for a short time (engine still hot) and it will 'usually' have quite a hesitation when you first press on the gas. After it starts going in a few seconds, I will have no further hesitations on that trip.

History--> Over the last 6K or so, I had a check engine light come on and it indicated my front O2 sensor was slow. No other symptoms so I reset the code and that one has not come back. About 5K ago I got a catalyst efficacy degraded. I decided to take it to the dealer. They replaced the converter under the 80K warranty - they made no comments about the o2 sensors.

My guess --> I have one or both O2 sensors that need to be replaced.

Questions -->

Does my diagnosis sound right?

Do I need to replace both or just the front sensor?
Is there an online site that has a good price on the sensors?

Thanks for the help!

Mike Behnke · Accepted Answer

Pony up for the Chrysler O2 sensor.  Stay away from Bosch O2 sensors,which Chryslers eat for lunch.Terry wrote:--

Morton Linder · Answer

My dealer has a handheld computer gadget that he plugged into the Caravan'sdiagnostic socket, and in 5 seconds he had a reading: upstream oxygen sensor isbad.Try it.MortonTerry wrote:

Terry · Answer

Ok - last night I went out and borrowed a scanner (obd-2.com scanner) . I put it on and read the O2 sensor voltage output. Something seems strange....

Sensor 1 look like I was told to expect - kind of a sine wave - going up and down from about .08 volts to a max of .98 volts -- that seems normal to me.

Sensor 2 - It started off with a sine wave, but the wave got smaller until it was a flat line. It would stay around .8 volts while it was idleing (around 760RPM). When I take it up to 1600 RPM it would drop and stay around .1 volts, then back to around .8 when I let off the gas.

I dont pretend to have a great knowledge of how these should work. But I just dont have the money to go out and start replacing sensors if that is not going to help me.

Does anyone have some advice based on what I am seeing?

Thanks in advace for the help!

o2 sensor bad?

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