The p0131 is 02 sensor, bank one. I can't say the sensor is faulty. I'd have to start by checking the wiring circuit.
P0300 is a random misfire, how long since a tune-up. Check the note below'
February, 7, 2011 AT 7:04 PM
As far as the heat issue, does the engine reach normal operating temp? Are the heater hoses hot? If you live in an area that is extremely cold, you may need to use a block heater.
February, 7, 2011 AT 7:19 PM
Thanks for the reply. Tune-up was done approx 1,000 miles ago. However, fuel filter has never been replaced. Would the o2 sensor code be caused by the random misfire (or vice versa)?
February, 7, 2011 AT 7:23 PM
The random misfire may have caused the other code.
February, 7, 2011 AT 7:26 PM
Ok, so what should I do to check the random misfire on random cylinders?
February, 7, 2011 AT 7:52 PM
Also, I believe the heat issue is related to a low coolant level. Thanks
February, 7, 2011 AT 8:10 PM
Below is the flow chart for p0300.
February, 7, 2011 AT 10:06 PM
I did see a couple of tsbs for that code. The possibilities are just about endless. One tsb was for a problem computer ground, G103 I believe. You take the ground loose, check the wiring, use a file or something and shine-up the contact surfaces. G103 is located, right rear of engine block. The other tsb was for water getting into the fuel system, caused by the evap harness, vacuum lines.