CEL on, code-P1123, any advice???

[JFP in PA]

P1123 is the code thrown when oxygen sensor on bank 1 reaches its limit trying to lean out an overly rich mixture. Normal suspects are high fuel pressure (bad regulator) or a leaking injector.

[Meat Head]

Originally Posted by JFP in PA

P1123 is the code thrown when oxygen sensor on bank 1 reaches its limit trying to lean out an overly rich mixture. Normal suspects are high fuel pressure (bad regulator) or a leaking injector.

Is there a way I can test to figure out the true problem (oxygen sensors / leaking injector / fuel pressure regulator)? I would like to avoid taking the car to a shop just to find out it was something I could have fixed.

When the problem is fixed, will the CEL go out or does it have to be cleared?

The car is running perfectly. Wouldn't a leaking injector cause the engine to run rough?

[JFP in PA]

Originally Posted by Meat Head

Is there a way I can test to figure out the true problem (oxygen sensors / leaking injector / fuel pressure regulator)? I would like to avoid taking the car to a shop just to find out it was something I could have fixed.

When the problem is fixed, will the CEL go out or does it have to be cleared?

The car is running perfectly. Wouldn't a leaking injector cause the engine to run rough?

I truly respect your opinion on these cars and any added information to help me fix this would be greatly appreciated.

The fuel pressure regulator can be tested by connecting a pressure test gauge to the test port on the engine's duel rail to see if the pressures are in bounds.

A slightly leaking injector may not even be noticeable in how the car runs, but could show up as diminished MPG.

You could also hook up a Porsche specific diagnostic tool (PST II, PIWIS, Durametric) to the car and read the actual fuel trims while it is running to see if one bank is running richer than it should.