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OBDII NOT READY - driving procedure

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So I tried to get my new to me 996 C4 Mk2 that was PPI'd with flying colors last Friday through emissions testing.

IT FAILED! There is no CEL.

It failed because of a "OBDII NOT READY" error.

Apparently if the battery is disconnected and reconnected it can give you this error as the sensors are relearning, and avoids emission 'cheaters'.

Perhaps during the PPI the battery was disconnected? Whatever the case is there a procedure to get the car to be OBDII ready quickly?

I saw this on the 993 section - does this apply to the 996 Mk2?

"That was my entry in response to jstahmann's need to run through the "readiness cycle". Our ever diligent fed & state smog patrol made sure that their evil constituents don't try to fool them by reseting the emissions trouble codes and dashing to the inspection station for a quick read before they trigger again.

At the same time the OBDII cpu codes are reset, the "readiness codes" are also reset. The readiness code indicates whether each of the 8 system sensors have completed it's diagnostic check. So the inspection station doesn't see a trouble code but also sees that the readiness code is off (actually it reads more than "0").

Once the CE light is cleared the following readiness cycle can be followed to reset the code or you could drive the car for a while in a variety of situations that would allow each system to do it's thing:

Start engine, idle cold for approx. 2 min, 10 secs.

Accelerate to 20-30 MPH, Maintain steady speed for approx 3 min, 15 secs.

Accelerate to 40-60 MPH, Maintain steady speed for approx 15 mins.

Decelerate and come to a stop. Idle in gear for approx 5 mins.

Following the start engine phase the sequence of test conditions may interchange.

routine will be discontinued whenever:

Engine speed exceeds 3000 RPM

Large fluctuations in throttle angle

Road speed exceeds 60 MPH

Hope this helps y'all.

The route that I took did have some starts and stops in it, but as long as you follow the instructions not to exceed 3k rpm, don't make large throttle fluctuations and don't exceed 60 mph until complete, it worked (as least for me).


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Had the same issue after I had the engine out of my car and put it back in. Went to the smog station the next day and the OBD was not ready. Drove the car for a hundred miles or so and them went back and passed with flying colors. Just give it a day or so and put on some miles, it will probably be OK.

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  • 12 years later...

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