P0150 Codes

[lomax]

To make a short story long, I have a 1999 996 C4 and it started throwing P1130 codes every few hundred miles. After reading all the wonderful information here I decided to replace the MAF and all of the O2 sensors. I ordered these up through Pelican parts as they were the OEM brand.

I installed all of these yesterday and everything was wonderful for about 40 miles then the CEL light came on again. At least this time it was a different code. P0150:
Porsche fault code 18 - O2 sensor ahead of cat. conv. Cylinder (4-6)

So does this mean that one of the new O2 sensors that I got is bad or do I need to look elsewhere ?

NOTE: the car has always run very smoothly with no idle problems.

I have cleared the fault and will drive it and try it again. If it continues to throw the code I will put one of the old ahead of cat sensors back in and see it that works. That would prove the new sensor is bad I assume.

Any information or advice would be greatly appreciated.

Marc

[JFP in PA]

Before you go swapping sensors unnecessarily again (your first code was for an overly rich mixture condition, not the sensors), the most common cause for P0150 is a wiring problem (short to ground, low voltage caused by a loose connector).

[lomax]

Thanks, I will investigate further.