Emissions Testing and OBD

[ekename]

Hi Guys,

Three of the emissions monitors read not ready when I had my emissions test this morning which resulted in a failed test. How do these get reset? The guy who was doing the testing said this would happen by driving around. Is this true? How far does one have to drive, if so.

Thanks,

Tim

Note - this is for a 99, 996 - posted in the 997 forum by mistake (oops).

Edited July 25, 2005 by ekename

[Loren]

OBD II can reset any emissions fault on it's own after a specified number of "drive cycles" (they vary depending on the fault). Or, you should have the fault codes read so that fault can be corrected. It could be something as simple as a loose gas cap or something more like a bad oxygen sensor or MAF. Either way they should read the codes, correct the fault and then reset the fault codes - then test the car again.

[ekename]

Hi Loren,

I had a code indicating that the enrichment limit had been reached on cylinder 4-6 but that has been corrected which resulted in the reseting of the computer to clear the CEL. I've made two 50 mile continuous drives since then but all the monitors (evaporator, o2 sensor and catalyst) are shown as "Not Ready" on the emissions report. I guess I need a few more drive cycles to get them reset.

Thanks,

Tim

[Loren]

Or... you can force a reset by using an OBD II scan tool or disconnecting the battery for a few minutes. If you disconnect the battery make sure you have your radio code.

[Tool Pants]

http://www.renntech.org/forums/index.php?showtopic=4331

[REDLINE WINS]

When ready status cannot be achieved it will not reset unless the fault issue is addressed and repaired. Resetting the DME to turn off the check engine light will not automatically achieve ready status. The vehicle will in time through drive cycles will achieve ready status ONLY if the fault or faults have been completely repaired. The technician can "short cut" the drive cycles by performing "short testing" with the factory system tester. If short testing is completed in all OBD aspects then ready status will be achieved.