I had this code come up PC0139 and I looked it up and it said this[*]P0139 - Heated Oxygen Sensor (HO2S) Slow Response Bank 1 Sensor 2[*]Does anyone know what it means?

 

Well it means your Oxygen Senosor that reads the exhaust condition on cylinder bank 1 detected an errorcondition. Sensor 2 is down line in the exhaust system I believe. For each side one is up at the manifolds then down in the exhaust sytem before the catalytic conversters.

They are almost the size of clothes pins and many people don’t even know they exist.The oxygen sensor is a measuring probe for determining the amount of oxygen in the exhaust and they are mounted inside of your exhaust pipe. Oxygen sensors do their job by continually monitoring exhaust gases and signals the engine computer to adjust the air/fuel ratio to make sure that gasoline combustion is as complete as possible, thus reducing emissions while also improving engine performance and fuel efficiency.

If the mixture is too rich or too lean, the oxygen sensor adjusts the amount of fuel that enters your engine accordingly. The wrong mix of gasoline and oxygen can increase pollutants that exit your vehicle – thereby harming the environment. This is also one of the causes of faulty catalytic converter and engine damage. Like any other car parts, oxygen sensors don’t last forever. The normal aging process will eventually cause the oxygen sensor to stop working. Probably $75 or less.

 

When I had the same code about my that I assumed that the problem was my Peugeot oxygen sensor and when I brought to my mechanic, he told me that this involves the rear oxygen sensor on the driver's side. That the code indicates the engine air fuel ratio is not being adjusted by the oxygen sensor signal or the ECM as expected to do so, or not adjusted as often as expected to do so once the engine is warmed or under normal engine use.
Anyway here is some causes that he told regarding the code P0139:
[ul][*]The oxygen sensor is faulty[*]The wiring to the sensor is broken / frayed[*]There is an exhaust leak[/ul]
The simplest thing to do is to reset the code and see if it comes back. If the code comes back, the problem is more than likely the rear driver's side oxygen sensor. You will likely wind up replacing it but you should also consider these possible solutions: [ul][*]Check and fix any exhaust leaks[*]Check for wiring problems (shorted, frayed wires)[*]Check the frequency and amplitude of the oxygen sensor (advanced)[*]Check for a deteriorating / contaminated oxygen sensor, replace if necessary[*]Check for inlet air leaks[*]Check the MAF sensor for proper operation[/ul]Hope this helps... Good luck!!!

 

It's not the drivers side o2 sensor on a 96 deville.
It will be the sensor furthest away from the engine after the catalytic converter(its not dual exhaust).
Almost exactly dead center of the car but facing the passenger side.
A heat shield is riveted to the under body which protects the wiring harness and connector.
You will need to drill out those rivets in order to unplug the sensor.