Erasing or clearing the check engine light is actually resetting the engine control computer (ECU). This not only turns off the check engine light but more importantly it erases any trouble codes and all the emission monitors. The "monitors" are internal tests which the ECU performs to check itself and specific systems related to engine emissions, i.e. the EGR system, the EVAP system, Catalyst, so on. In this specific case it appears all your Toyota Camry's monitors were erased due to the reset. You will need to complete a Toyota Camry drive cycle in order to set the emission monitors (make the monitors complete).
The Toyota Camry drive cycle below is designed for automatic transmission equipped Toyota Camrys' with 2.2L engines and CA approved emissions.
1998-2002 Toyota Camry Drive Cycle (Engine 1MZ-FE & 5S-FE - CA Emissions Certified)
Begin by: (Make sure you have between 1/4 and 3/4 fuel in the gas tank. The EVAP test will not run while your Toyota has a full tank of gas or the gas tank is near empty). Ensure there are no pending or active trouble codes and that the check engine light is not on.
A. Start the engine and allow it to idle for 2 minutes or more.
B. Drive the vehicle at 40-70 mph or more for at least 3 minutes. Be sure to maintain engine speed between 900 and 3,200 rpm.
C. Stop the vehicle and allow the engine to idle for 10 seconds or more.
D. Drive the vehicle at 25 mph for at least 40 seconds or more. Be sure to maintain engine speed above 900 rpm.
E. Stop the vehicle and allow the engine to idle for 10 seconds or more.
F. Perform steps “D” and “E” ten times.
G. Drive the vehicle allowing speed to fluctuate between 35-45 mph for about 16 minutes.
If readiness status of all monitors do not switch to “complete,” ensure preconditions are met, turn the ignition switch OFF, then repeat steps “A” through “G.”
Completing the Toyota Camry drive cycle above should set the emission monitors required to pass the smog check. We recommend performing the drive cycle 2 or 3 times before the smog inspection.
Take caution when performing drive cycles on public roadways. If you feel you will be unable to complete the driving pattern above safely and legally, seek assistance from a reputable smog check repair station or Toyota repair facility.
