originalmotorhead

Got these 4 codes on my 2000 2.7 boxster:
p0159
P1118
p1275
p1276

History: I installed headers recently. The back two(secondary, post cat) O2 sensors are now screwed into a little capsule so they don't get dirty but are still connected and grounded to the car. These were some cheepo fleabay headers and the primary O2 bung is in one of the header output pipes, not where all 3 collect together. I've run a tank of gas, or two thru and not noticed any significant fuel consumption changes.(maybe from 27 to 25)

Car runs like a spanked dog. Am thinking I get these codes because the secondary O2's are not reading anything.

Ideas ?

Tom

originalmotorhead

Forgot to mention, i did some searches and found mixed results for the codes.

p0159 - secondary o2 passenger side (bank2, sensor2)
p1118 - o2 sensor heater open, bank1, sensor2 ? or manifold absolute temp low
p1275 - pre cat o2 for cyl 1-3?
p1276 - Other bank o2 ?

I am wondering if I need to relocate the o2 sensor from the single header output to where they all merge(3 into 1).

again, car drives, idles, fine. not noticed any absurd difference in fuel consumption.
Tom

Macster

sensor is positioned so it is constantly in the exhaust gas stream from all cylinders. The sensor must be hot to work properly and the heater helps but exhaust gases are counted on to supply some of the heat necessary for sensor to function.

As I think you are on the road to learning, there is more to a *good* exhaust system than meets the eye.

In my opinion no aftermarket exhaust system is worthy of being used if it 1) Causes CELs or in some way causes the engine controller to have to venture towards the lean or rich threshold limit to get suitable readings from the #2 sensors which of course measure converter efficiency; 2) Does not deliver some additional HP/torque; 3) Does not deliver acceptable levels of noise (which for some ears can be louder); 4) Requires modification to the existing exhaust hardpoint attachments; 5) Is fragile.

Sincerely,

Macster.

originalmotorhead

Quick update.

I started another post with pics but after relocating the o2 sensor position, i eliminated the primary o2 codes. i still have secondary o2 codes because they read stagnant but i plan to fool that one out with a little timer circuit on the sensor. but for now, i'll leave the light on and enjoy the car.

but check out my other post, titled insides of stock muffler. i also have pics of the headers.
Tom

Macster

reasonably close enough to avoid a CEL but the Ecu will not be able to adapt to changing conditions properly and engine performance, economy, not to mention emissions will suffer.

Besdies the Ecu's got a pretty sophisticated algorithm for checking for proper O2 sensor operation and tampering and I suspect at some point it will detect the #2 O2 sensors are not responding properly and set the check engine light.

The Ecu wants to see some subtle tracking by the #2 O2 sensors of the #1 O2 sensors as the #1 O2 senors swing between indicating too much oxygen to not enough oxygen in the exhaust gas stream. This variation is under Ecu control.

Sincerely,

Macster.