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How many mile do I need to put on my car to reset codes for smog check

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It's time for my California smog check so I must remove the K&N air intake and reinstall the stock air box, I am faily certain I will need to diconnect the battrie inorder to reset the CPU, The question I have is, how many miles will I need to drive to reset the obd codes before I can pass smog. I just got my Reg. info yesterday and must get the smog ckeck on monday as I am having screws put in my left foot on tuesday and will not be able to drive my car for three months ( Can't use the clutch with a cast)

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Disconnecting the battery will not erase codes in the DME/ECU. You will need a code scanner to clear the memory. Also, I believe that California requires all readiness flags be set for the emissions check. If you reset the computer and then take the car in you will be failed and told to return when all readiness tests/flags are complete. Depending on your driving, this could take a day or two to complete.

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Why would you need to reset the DME?

Just change the air box and take it in.

If you have no CEL or pending codes then you should pass.

Thanks Loren, I appriciate the help.thankyou.gif

and, of course, remember your first amendment rights...

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@ goldenwarrior1, eventual fault codes and actual values, stored in the DME, and relating to the environment will be erased by disconnecting the battery. That's mostly the problem in environment test performing.

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@ goldenwarrior1, eventual fault codes and actual values, stored in the DME, and relating to the environment will be erased by disconnecting the battery. That's mostly the problem in environment test performing.

RFM, True, however the code itself will not clear until manually reset or the vehicle completes enough drive cycles after the fault is fixed or goes away. Unless of couse I have misunderstood somthing!

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The 996 OBD II manual states that, when faults have been erased, two "trips" are required to "initiate" the "readiness code". A trip is defined as a period of time, not miles, specifically 1150 seconds.

I've inserted the two definitions for Readiness Code and Trip (note the clause regarding power disconnection):

Readiness code The readiness code indicates that the required fault checks were performed by the OBD system. It is not important whether or not a fault was found. The readiness code is reset if the fault memory is erased or the power supply (terminal 30) is cut off when a code is stored. The readiness code is not reset when the battery is disconnected if no fault is stored. To initiate the readiness code, at least two trips have to be completed.

Trip A trip is a driving cycle after a rest period that enabled the diagnostic system to monitor all components and systems at least once. In the event of a fault, it may not be possible to perform all diagnostic routines under certain circumstances. For this reason, a replacement trip is recognized after an operating period of 1150 seconds. In other words, a driving cycle is recognized as a trip after this time, even if not all diagnostic routines were performed.

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