Invius

Quick background -- owned my 996 for 4 months, no issues. CEL came on today on the way to lunch. Hooked it up to PIWIS cable when I got home, showed 2 codes. Doesn't appear to be running any differently than it was yesterday, or since I bought it...any recommendations here would be helpful. I cleared the codes to see if they reset...which I figure they will. Anyone else have these codes before, what was the issue/solution...was it a DIY or a indy kind of problem?


P0134
Porsche fault code 10 - O2 sensor ahead of cat. conv.
bank 1


P0446
Porsche fault code 95 - Shutoff valve activated
charcoal filter (function)

Invius

Btw, meant to say thanks for the help.

redridge

hmmm, gas cap on tight?

Invius

Thought about that after I posted -- I filled up yesterday, and don't believe too much in coincidences... I need to go crank it down tight to make sure, but I'm guessing that's probably part if not all of the problem.

Gonzo911

Got the same/similar codes shortly after filling up (also early in my Porsche ownership). Turned out I had a cracked seal on the gas cap.

Macster

IIRC P0134 is O2 sensor ahead of converter (bank #1, cylinders 1-3) interruption of signal.

Fault condition is an interruption of the signal wire or ground wire of the O2 sensor. This is a wiring harness problem, or a sensor problem, or an ECM problem.

My WAG would be the sensor is bad.

Test 1: Wiring harness test: Disconnect all 4 sensors. Turn ignition switch to on. Connect digital voltmeter to sleeve pin 3 and 4 of the sensor connector 1 ahead of the converter. Measure approx. 450mV.

Connect a digital voltmeter to sleeve pin 3 and ground.

There's a caution: Do *not* use the ECM ground terminals when measuring input/output voltages or signals. Doing so may result in damage to the ECM or other components. Use a ground other than the ECM terminals, such as battery ground.

Specification: approx. 720mV.

Start the engine and run at high speed [fast idle] for 3 minutes. Connect a digital voltmeter to sleeve pin 1 and 2. Read battery voltage.

Test 2: checking oxygen sensor function. Road test vehicle to bring engine up to operating temperature. Connect scan tool and read voltage of oxygen sensor ahead of converter. Reading should fluctuate between 100mV and 800mV.

Test 3: checking oxygen sensor heating. Disconnect sensor 1 plug connector ahead of converter. Connect digital ohmmeter on pin side to pin 1 and 2 of the oxygen sensor plug connector. Meter reading should be 1.4 to 2.5 ohms at 68F (20C).

Connect ohmmeter on pin side 1 and oxygen sensor housing. Read infinity.

Connect ohmmeter on pin side to pin 2 and oxygen sensor housing. Reading should be infinity.

P0446 I'd worry about later. I do not think it is that big of a deal. It may be as others have suggested the gas cap.

However... fault condition is below lower limit. Purge air line blocked; flow resistance of EVAP canister too high.

None of these read like a gas cap loose or leaking.

Sincerely,

Macster.

Invius

Interesting about the cracked seal, I'll take a look at that and see if that's the case.

Macster, thanks for the info. I'll hook it up to the PIWIS cable and see what kind of reading I am getting from it, and if it is within normal limits. As a DIY, how hard is an O2 sensor to replace if I need to? Also, do you usually do them both at the same time, or as needed?

Thanks,

DS

redridge

Ive gotten these faults..... checked the gas cap and it was gone. Damn NJ gas attendants.....

geetee

It could be gas cap but my bets on regeneration valve. I've got those codes...checked gas cap etc etc....seemed fine for a few fill ups and got hit the the codes again. Searching through a few forums, I changed the regeneration valve. Takes literally 2 minutes and part is 100 or so.