Kika

Will the OBDII system throw a P1411 if the oxygen sensor monitor is NOT set, i.e. incomplete?

I have been getting P1411 codes, and I use my reader to reset them so the CEL goes off. All 5 monitors in the drive cycle go to incomplete or not set. As I drive, they start to set. The last one to set is usually the oxygen sensor monitor.

the question usually comes up as to when the P1411 comes up, but I wonder if I should count the miles/time when the oxygen monitor is not set.

I asked 3 known local mechanics, and they all said that it didn't matter, the system should show a fault as soon as it occurs, regardless of monitor status.

This is not what I am seeing however. CEL has not come back on, but the monitor is incomplete.
Anyone know?

nine9six

Keith,
I am thinking once the CEL has been cleared; until the monitor status has been reset, you should not get a CEL.

My thoughts are not based upon knowledge of the system, but rather logic in the terminology being used..."Monitor Status"

Until "monitor status" is in a ready state, how would it recognize another fault? I think this forces attention to the issue, which I believe, is what is intended.

If it were me, I would send an email to Lorenfb of Consulting Services, and ask the question. He is a great asset, and very good at what he does.
p.s. And he's somewhat local in Manhattan Beach...

Kika

Paul,

I agree with you and that is my logic as well, I would just like to confirm my hypothesis with someone that has more working knowledge of how the OBD II system actually works. In any event, I dropped off my car to have it smoked, I am hoping there is a vacuum leak that is the cause.

TJ993

my car will Ping Ping out the exhaust

the o Monitor is Not set.

As soon as I complete the drive cycle, (particularly the second drive cycle, 2:15 wait 4 pump to finish, then 3:15 20 - 30 mph then do the long 15 minutes at 40 - 55 mph then sit in neutral and idle for 5 minutes)

I let the car sit overnight

come out next day and No CEL - Last weekend

Then I drive
motor soiunds crisp and it pops

then my cel returns

Last to set is the "o" monitor

The Ping I now believe is the DNE retarding ignition timing thinking there is a problem

Lorenfb

"I asked 3 known local mechanics, and they all said that it didn't matter, the system should show a fault as soon as it occurs, regardless of monitor status."

That is totally correct! OBDII monitor system is basically an independent system which checks the functionality
of the emissions system under various operating conditions. The fault monitoring system that generates CELs
evaluates whether the DME ECM and its inputs & outputs are operating properly.

nine9six

Thanks Loren!

Kika

Loren, thanks!

Let's assume I have a clogged SAI port then. The system triggers a P1411, which I then reset, so the CEL goes off and the 5 drive monitors are now incomplete.

Since the clog still exists, why doesn't the CEL immediately come back on?

In my case, I am hoping/thinking it is a vacuum leak somewhere in the system, but even so, since the leak is still there, shouldn't the CEL also immediately come on?

Or is there some other issue that takes time to manifest itself?

Lorenfb

"Let's assume I have a clogged SAI port then. The system triggers a P1411,
which I then reset, so the CEL goes off and the 5 drive monitors are now incomplete.
Since the clog still exists, why doesn't the CEL immediately come back on?"

Since the SAI test only runs when the engine is cold at start-up by the
OBDII emissions monitor tests, the DME ECM diagnostics does know or
'see' a problem yet. The OBDII emissions monitor tests needs to run the
SAI test before a fault code happens. When it does run the SAI and
it fails, the OBDII reports the failure to the DME ECM which sets a CEL.

Bottom line: You have a CEL "grace period" until the SAI test is again run.

nine9six

Keith,
What were the results of your smoke test for vacuum leaks?

Kika

Mechanic still has the car, backlog of cars is in front of me, probably going to be a few days before he can get to it.

Thanks Loren. What is interesting, is that my CEL typically comes on during a drive, not at start up. The last few times have been 20-30 minutes into a drive, on the freeway cruising speed.

That is why I suspected the code was perhaps stored, but did not trigger the CEL until the monitor was set, which typically happens during a drive.

Boy, what I would give to understand all of the logic that is in the DME...

nine9six

Perhaps only the Porsche design engineers truly know for sure...This logic certainly seem counter-intuitive.

ToSi

The diagnostic for SAI likely uses the O2 sensor as an input.. either during the initial cold start, or during the intrusive idle test (pump runs first time you stop at a light once car is warm). As such, it won't declare the SAI faulted (P1411 or P0410) until the O2 sensor can be trusted, i.e. after the O2 monitor completes.

Per CARB regs, the code needs to set within 10sec of the fault being detected (assuming inputs are valid, as above) but the MIL doesn't need to illuminate until the fault occurs again on the 2nd consecutive drive cycle (exception is the flashing MIL for misfire).

Since you're only setting one bank, it's likely a clog is the cause although if the other side is marginal, might still be something on the supply side too. Might try blowing out the system & checking for leaks around the check valve. Either way, something's broke.. open up that wallet!

Kika

That is what I was thinking, and seems to be what I am experiencing, no fault, until the oxygen monitor is set.

For the record, my Actron 9180 only shows P1411, but the Bosch Hammer shows both P1411 and P0410, so I think there is a deficiency with the reader as well.

Lorenfb

"The diagnostic for SAI likely uses the O2 sensor as an input.. either during the initial cold start, or during the intrusive idle test (pump runs first time you stop at a light once car is warm)."

The O2 sensor is used during the cold start SAI test. If one has the Porsche tester, one can see
the O2 voltages as the test is done.

"As such, it won't declare the SAI faulted (P1411 or P0410) until the O2 sensor can be trusted, i.e. after the O2 monitor completes."

Actually, the fault will occur once the SAI is completed. Again, use of the Porsche tester will
indicate this.

"Per CARB regs, the code needs to set within 10sec of the fault being detected (assuming inputs are valid, as above) but the MIL doesn't need to illuminate until the fault occurs again on the 2nd consecutive drive cycle (exception is the flashing MIL for misfire)."

That's questionable, as Porsche and other European OEMs did not implement ODBII to the letter but
still complied.

"Since you're only setting one bank, it's likely a clog is the cause although if the other side is marginal, might still be something on the supply side too. Might try blowing out the system & checking for leaks around the check valve. Either way, something's broke.. open up that wallet!"

Guessing without actually monitoring the Q2 voltages is basically a waste of time and potentially money.

Bottom line: When having problems setting the 993 monitors, one needs access to a Porsche tester.

Kika

This is the conclusion I have come to.

Generic readers are useful, and can help for some things, but they also have limitations.