Chrysler Repair: Chrysler 300C 2005; code 0520

Question
Hello Roland!  My check engine light came on early this morning, I took it to Auto Zone and had them check to see what code was causing the light to come on, P0520.  They gave me a readout, first thing was to check the oil, which I did.  It was low, added oil....the light is still on and it is now early evening.  I had read an earlier answer to this very question you had answered--I am assuming there wouldn't be much difference from the 2005  to the 2006 models via the wiring and the color of the wiring?

Thank you!
Lisa

Answer
Hi Lisa,
The check engine light for a fault code doesn't automatically extinguish itself when you correct the problem, unless Autozone purposely erased it after they did the readout. You have to purposely erase the code and then watch to be sure that it doesn't return. To do that you would disconnect the - post clamp from the battery for about 30 seconds, then reconnect it. That will do the trick.
Let me know if it returns and we'll check into the wiring for the oil pressure gauge system. The battery is located in the trunk, under the floor panel. Be sure to do the disconnect at the - post.
If the light comes 'on' again, then try to notice if that happened when you were in motion or at idle. It is possible that the idle oil pressure is low due to the wearing of the engine if you have a goodly number of miles on it. You can correct that issue by increasing the 'weight' of the oil one step the next time you have the oil changed. That automatically increases the oil pressure at any engine speed.
The wiring of the system would be the same in '05 and '06.
What does the oil gauge show at idle, and when you are at road speed?

Addendum:
Another possibility is that the oil pressure sensor is leaking oil and for that reason it is also reading inaccurately low pressure. That would explain why the 0520 code came up and also why you are loosing oil. Do you see and oil spots on the ground where you park your car overnight? If so, than if that were under the location of the pressure sensor that would cause me to recommend that you look at the sensor to see if there is oil dripping from it and/or running down below it. It is located immediately adjacent to the oil filter. If it is leaking then that is an inexpensive part to buy and to change out yourself. Tell me which engine (L) you have for specific directions.
Let me know what you find.

Please read the PS below and respond to it.
Thanks,
Roland