Re: Lots of seemingly unrelated errors my first thought has to be ...

I have a 2000 boxster S with 78K. I have owned it for 3 years, driving it from May to October in MN. It runs great except for this weird hard miss once in a while, but no one seems to know what causes it. Any way it doesn't happen often an it doesn't bother me much. The issue I have is the CEL keeps coming on displaying some codes I will list below. It also constantly cyclically idles from 625rpm to 825rpm. If I turn on the a/c it stops and idles fine.
I have cleaned the MAF and throttle body, which looked clean to start. I though it would be a vac leak so I took it to a local shop and they smoke tested and found nothing. It is easy to remove oil cap when idling and not much happens except the idle goes up until cap is put back on, so I don't feel it is the AOS, which I replaced with a new one. I have access to a DuraMetric scanner which is how I got the codes below. It is a 4+hour round trip to the nearest dealership, which I will avoid like the plague. Any help would be much appreciated. THANKS!

P0327 Knock sensor 1 short to ground
P1130 Oxygen sensing adaptation idle range bank 2
P1505 DVE control range open circuit
P0134 O2 sensor ahead of cat. conv. Cylinder 1-3
P0133 O2 sensor aging ahead of cat conv. cylinder 1-3 below limit value
P1275 Oxygen sensor aging delay bank 1 below limit value
P0507 Idle air control system exceeds limit value
P1576 Cruise control readiness light via CAN exceeds limit value (my CC just quit working, I read in forum that if bulb goes out CC won't work, I have the bulb and will install tmrrw)

Quick add here. I replaced the bulbs that Pelican guys said was cruise, but I think the real bulb is inside instrument cluster. Does anyone know if that is true. I saw an old post that said if the bulb in the instrument cluster is out, the CC will not function. My CC worked fine for three years and now its gone and it displays the code detailed in original post.

I would start by checking the things you've recently touched.

rodent damage.

I note the car is off the road from Nov to April. That's longer than it is on the road. Plenty of time for the critters to wreck havoc.

Consider the errors…


Knock sensor error: Short to ground. That implies a wiring problem.

The P1130 suggests an air leak. 'course, right off the bat I'd mention AOS, but you report replacing that. I'd then offer the suggestion that you double-check your work or consider the new one defective.

There is also the possibility of an oil filler tube cap leak. (Failing to spot a leaking oil filler tube cap had me replacing a perfectly good MAF.)

Some errors could suggest a bad MAF.

The P1505 error points to the throttle body. (Throttle jacking control unit range fault, or something like that.)

There there are the aging O2 sensor errors.

Next comes the idle air error.

Last but not least the cruise control error.

I would find it hard to believe the car has a bad knock sensor, the O2 sensors just decided to all get old at once, the throttle body wore out, something's amiss in the idle control, the MAF is acting up, and the cruise control decided what the heck might as well join in.

All over the map.

I think I'd start at the knock sensor. That short to ground knock sensor error… I'd look very carefully at the knock sensors the wiring for any signs of rodent damage.

You have to look very closely. I was shown a Cayman in for rodent damage. A vapor line from the fuel tank to the engine compartment was gnawed through. The mouse probably stopped when he broke through the wall of the plastic tube and got a big whiff of gas fumes from the line. But there was just a small spot where the gnawing was. And the line was hidden by the plastic paneling that covers the bottom of the car. These had to be removed and expose the lines.

Wow. Thanks for all the good info. I will start checking this stuff out. I was checking around the oil cap and dipstick and when I pushed the dipstick back in, it pushed through the housing. So it is broken but the stick still seals perfectly with the tube. I will have to check the rest of the tube to make sure it is not broken further down. I will also get new oil cap for fun. Thanks for the info!

Many errors can be caused by other problems. In the service manuals many of the errors explicitly say (paraphrased) "only valid if in the absence of other errors".

One common cause of leaks (which could have been exacerbated by the AOS replacement) is the bellows tube on the oil fill line. But there are so many. I would start with checking the lines you unplugged to replace the AOS, then I would move to the vacuum lines, which often get accidentally knocked out when doing other stuff.

for any installation problems or collateral damage from the installation would be advised.

At the same time one look for rodent sign and rodent damage sign.

Rodents or not, i think the codes themselves are likely to be the result of some different damage - broken wire, chewed through wire, wet wire, etc - something that is causing seemingly unrelated codes.

What has happened reacently? Service? Car out in rain? etc.

Rodents a real possibility too...

Best of luck.

Grant

Grant

gee-lenahan-at-gee-mail-dot-com

The fun doesn't end. Went to go to dinner on Saturday and it started revving between 1000 and 1800 cyclically. Disconnected MAF and reset DME. Idles like a top at 725. Drove it, but will not really pull beyond 5000rpm. Checked MAF and it is the Bosch ending in 125 01. I have an early 2000 and info on web says that model should have the Bosch ending in 124, unless the DME has been upgraded for the 125 01 version. Porsche says they do not have a unified dealer network system so they cannot tell if the DME has been upgraded, which I am quite sure it has not. Trying to contact former owner to see if he did it. Yeesh!

I still think the problem is probably a vacuum leak.

Thanks for all the good advice. I ordered what I believe to be the correct MAF sensor and will install it tmmrw, clear all code with Durametric and report what happens. In my original post I mentioned this code:
P1576 Cruise control readiness light via CAN exceeds limit value
My CC readiness light, green light in bottom right of speedo, quit working and the CC does not work either. I saw an old post that said if the bulb burns out, the CC will not function. From the above code, that seems plausible. Does anyone know if it is true? Replacing the bulb inside the gauge housing is a little hairy and I don't want to do it and find out that it is not the issue.

P1579 error.

You are either faced with replacing the burned out cruise control light or trouble-shooting a shorted or broken wire: P1576 Cruise Control Standby Lamp – Above Limit, or Below Limit, or Open Circuit Possible causes: – Short circuit to B+ in wiring – Short to ground in wiring – Break in wiring Check wiring from DME control module, pin IV/18, to instrument cluster, pin I/16, for short to B+.

Just make sure to put a towel under the cluster when you lift it to avoid scratching the leather.

[www.pelicanparts.com]

which can cause the problem you described if they are misaligned. Boxsterra is right, changing the bulbs is not that bad (good tip about using a towel to cover the dash leather). Good luck.