02 Boxster S header/O2 help?

[edevlin]

Boy does this sound like a familar story. When I put on headers and high-flow cats I ended up replacing my oxygen sensors, redoing the wire extension to the rear sensors and even replaced both my cats. Every time we tried something, I was still getting a CEL after 100 miles or so. We tried moving the location of the sensor bungs, moving the sensor into and out of the gas stream, still got CEL. I find it interesting that some folks put on headers and extend the wire to their oxygen sensors and never get a CEL, not me.

In my case, the shop that installed the headers and high-flow cats also wrote the software for, and installed the chip in my car. They ended up going into the ECU and slightly changeingthe threshold whereby the CEL was triggered. It has been 15K miles and the car is running like a top and no CEL. BTW, all the time I was getting the CEL, the car was still running great, the light just drove me nuts. Best of luck with your CEL, not sure what to offer other than what my experience was,

Ed

[blue2000s]

Maybe a larger gauge wire for the sensor extension will lower resistance enough to keep the signal to the ECU within the expected range?

[dmenn]

Here is the description of the codes from the Durametric Tool:

P0133 - Porsche fault code 15 - sensor ageing behind cat (conv. cylinder (1-3) below limit value)

P0153 - Porsche fault code 21 - sensor ageing behind cat (conv. cylinder (4-6) below limit value)

This is saying that the voltage on your post-cat O2 sensors is too low. Are they in the stream of exhaust gas? I know when I initially put headers on I just tied up the sensors in the engine area and didn't put them in the exhaust flow. I got both of these codes because the O2 sensor wasn't reading any exhausts gases. The engine computer was smarter than I thought.

If the catalytic converter is doing its job, the voltage should read a lower voltage than the pre-cat O2 sensors. You'll see major flucuation in the pre-cat O2 sensors from between .1 to .8 volts. I haven't driven the car much since putting my post-cat O2 sensors in on the car and extending the O2 wires, so I can't comment on the voltage yet for my post-cat O2 sensors and if any CEL will go off. So far though, nothing yet.

[easyc]

just find a Porsche PST2 and have someone scan your DME to ROW

[tholyoak]

When you extend the oxygen sensor wires you must ensure that the signal wire and the signal ground wire are extended as a twisted pair.

-Todd

[Sammy]

Originally Posted by tholyoak

When you extend the oxygen sensor wires you must ensure that the signal wire and the signal ground wire are extended as a twisted pair.

-Todd

Interesting advice... what is the reason for the twisted pair? Can I simply twist everything including the heating wires? Thanks!