What should the voltage range be from cold start to running temp?

What voltage would set off check engine light?

My daughter recently purchase a 03 SX 2.0 and previous owners said they replaced O2 but were unable to reset check engine light.

Start car and allow engine run for a few minutes voltage drops from 1.275 to around 0.8.
Shut car off then clear code and car is fine till next cold start.
At full operating temperature voltage drops to around 0.12 volts.

 

The voltage usually shouldn't go over .9V or so. A warm 02 should switch fairly rapidly between .1 and .9V. But it depends if you are talking about the 02 upstream or downstream from the cat.

 

The one in the manifold....upstream

 

It's usually not normal to go over 1V.

http://www.autodiagnosticsandpublish...or-testing.htm

 

The Chrysler O2 sensor is a little confusing. Chrysler is the only manufacturer that runs a 5v reference to the sensor. Supposely if there is a sensor plug in and functioning, the 5v reference drops to 2.5V. and the voltage you atually read on the scanner or when you back probe it is 2.5v minus the voltage the Sensor is producing.
Something like that... I don't remember what's the exact math equation, but there are quite a few article online if you Google it.

But from my experience, Most of the O2 sensor codes' "failed repair attempt" is due to the mechanic is using the Wrong O2 sensor. A lot of Part store sells the European Bosch O2 sensor, which doesn't work on most Domestic and Asian cars. I have no idea why Bosch doesn't fix it.

I would recommend you to just throw in another O2 sensor, a Factory one from your Dodge dealer. If no Dodge Dealer near you, and you have to use Aftermarket, buy brand "NTK" or "Denso" oxygen Sensor.

 

I think you're referring to a UEGO 02 sensor, I believe these vehicles are equipped with conventional voltage producing 02 sensors.

 

Chrysler don't use Wide Band O2 sensor, They are conventional O2 sensor, no different from Ford, Toyota, or GM. They probably have an identical sensor too. But it is Chrysler's way of monitoring the sensor that's different from other automaker.

If you look at other manufacturers O2 sensor Data with a Scanner or a Meter, it almost never go above 1 volt. However, Chrysler one, even tho the sensor only produce 0.1-0.9v, however, it will occasionally go over 1 volt, which is normal due to the fact that the PCM is atually running a 5 volt reference to the circuit.I am saying it is normal if you see like 3.14 volts occasionally on a Chrysler O2 sensor Data. While If you see like 1.87v on a GM vehicle, that means you got a electrical problem.

 

Not sure if I have an answer to my question or not.

I believe that the new O2 sensor that the last owners put in is not correct for car or is faulty.

Therfore I am gong to get a new one.