How long does the engine store any codes?

 

im pretty sure they are stored until they are cleared. im not aware of any type of expiration on codes.

 

Recap of the FAQ: http://forums.maxima.org/showthread....5&pagenumber=4


What is a MIL(aka. Check Engine Light) and how do I RESET it?
MIL QUICK Summary

Let me explain some things about how the OBD-II(On Board Diagnostic) System works on our car.

MIL - Malfunction Indicator Lamp(aka CEL - Check Engine Light)
DTC - Diagnostic Trouble Code

1) There are different "conditions" and "modes" that trigger a MIL to come on. Basically, if a problem is detected ONCE the 1st Trip DTC is stored. If the SAME malfuction is detected TWICE the 2nd Trip DTC is stored AND the MIL comes on. If the vehicle is driven 3-times with NO malfunction the MIL will turn off. If another happens the counter is reset.

2) Most DTC and "freeze frame"(sensor values/operating conditions when the DTC was logged) are stored until the vehicle is driven 40-trips. Therefore, your dealer will know what triggered the DTC(ex. 100+% WOT on a 2K2). A trip is not necessarily one start/stop of the engine. Your ECU must see the same A, B , C type "driving pattern" in which the ECU detected the malfunction.

3) For Misfire and Fuel Injection Systems the DTC and freeze frame are stored for 80-trips withOUT the same malfunction recurring.

4) Some scan tools such as the one I bought from http://www.obd-2.com/ will clear the DTC and turn off the MIL. Also, either a Scan Tool OR unplugging the POSITIVE OR NEGATIVE(easier) battery terminal for APPROXIMATELY 24hrs.(sometimes LESS) will erase:





DTC

1st Trip DTC

Freeze Frame Data

SRT codes

Test Values

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