OBD readiness resetting when ignition is turned off

[doug maire]

Last week I had my bad rear o2 sensor replaced and afterward the shop erased all the obd error codes from the OBC. I then drove the car the necessary distance and time to restore the computer back to readiness for my emission test. When I tested at the emission station the informed me it failed and was "not ready" to be tested. So I drove around some more to make sure all the sensors had a chance to reset. The second trip to the emission satation yielded the same result. The third time I purchased my own OBD reader and kept it connected as I drove around until all the sensors were cleared. I then took it to the emission station the third time and just as before it failed, All the obd data had been lost again. As soon as I turn off the ignition I must be loosing power to the on board computer. It is acting the same as disconnecting the battery and resetting the obd. Has anyone experienced this problem.