awhile back i got a CEL for a bad airflow sensor, which i replaced on my own and reset the CEL light by disconnecting the battery.

i was wondering if disconnecting the battery will also clear the code from the computer, or is the code still in memory?

the reason i'm asking about this is because my local mandatory emissions testing procedures are changing for obd2 vehicles (i have a 99 gs400) and they will be looking for stored codes which depending on the code, may result in a fail.

 

The code should be out of the system. I usually unhook both battery cables for at least 15 minutes to get any juice in any capacitor out of the system. I ran a test where I cleared a code this way and then checked with my handheld OBD2 scanner and nothing, not even old codes in the system.

However, doing this will also reset the readiness monitors (to see if O2s and cats are functioning) and used to get everything A-Ok according to the readiness monitors, you need to run the vehicle through its drive cycle. My uncle has a an OBD2 scanner that checks this (autozone should let you use one for free to check it) and I have found that after about 50 miles or 1 hour of pure driving the readiness monitors show OK.

 

lexmex... thank you for that info.

i believe it is the readiness monitors that they do check for... after a year of driving since i had done this reset, do you anticipate that i will run into any problems?