Cadillac Repair: Emissions service - check engine soon displayed, heater element, oxygen sensor

Question
Hi Bill,

I just bought a 96 Deville (had e-mailed you about the heated seats and trunk pull-down) and it appears it has a problem.  The Service Emissions command came up on the dash as well as the constant "check engine soon" command.  I did some research on-line and learned how to display the codes which I did.  The only code to appear read PC0139.  Which according to one website means "P0139 - Heated Oxygen Sensor (HO2S) Slow Response Bank 1 Sensor 2."  Is this correct?  How much will this cost to fix on average?

I literally just bought the car on the 6th of Jan and don't even have the title from the dealer yet.  Is this something that they could have known when selling it to me?  In reading on-line it appears you can reset the computer and in some cases the command will not reappear for a while.  
I'm not sure how to approach the dealer as I did not buy their warranty, it didn't seem to cover much anyway.

Any help in interpreting this problem would be appreciated.

Thanks,
Jeff

Answer
Hi Jeff, The code and the info you found agrees with the service manual information I have. What usually happens is the heater element goes bad and then the sensor takes longer than it should to warm up and that sets the code. As for prices you will need to call around for an exact price but the sensor $60, 1 hour labor to diagnos and 1/2 to 1 hour to install the sensor. If you can turn a 7/8" wrench and can get the car up safely on jackstands then replaceing it is should be doable for you. It is the sensor just in front of the catalytic converter.
The light could have been reset before you took a test drive or it could have been a coincidence but it should have turned on the light if you took a 20-30 minuit test drive. If you talk to the sales manager or salesperson some places have a warrenty period that some things will be repaired with-in a 30 day period from when you bought the car. As for warrenties some of them aren't worth the paper they are printed on or cover very little or won't cover preexisting conditions. You really have to read all the wording and ask the service manager what is really covered so there aren't any surprises come repair time. Hope that helps explain things. Bill