If you take your 2001 Honda Odyssey to the state emissions testing facility shortly after suffering a power failure from a dead or disconnected battery, they might tell you to come back later due to the detection of pass codes in the PCM. In order to clear these pass codes and generate ready codes, you'll need to put your Odyssey through a standard drive cycle. This will require about 30 minutes over a ten hour period.
Fill the 2001 Honda Odyssey's tank with gasoline until it's approximately 3/4 full. Drive the Odyssey to a parking area where you can let it sit for 8 hours where the ambient temperature is between 20 degrees and 95 degrees Fahrenheit.
Start the Odyssey and let it idle for 20 seconds without stepping on the accelerator pedal. Increase the engine RPMs to 2,000 and hold it at 2,000 until the engine temperature gauge climbs to at least 1/4 of the scale on the gauge, which will take about 3 minutes.
Choose a nearby highway with minimal traffic and drive the Odyssey at 50 to 60 miles per hour. Drive at a continuous throttle position for at least 90 seconds, as long as it's safe to do so. If you cannot drive for 90 seconds continuously, drive for three segments of 30 seconds each.
Exit the highway and drive the Odyssey in normal surface street conditions for 10 minutes. Allow the Odyssey to coast, with no acceleration or braking, for several seconds, several times, during this period to complete the drive cycle.
