Your smog technician may very well be correct, but it depends on your vehicle's model year. Different model year vehicles have different emissions monitor readiness requirements. Whether your vehicle is gasoline powered or diesel powered makes a difference on the number of incomplete monitors allowed too. The Bureau of Automotive Repairs has reduced the number of allowed incomplete OBD II emission monitors, also known as Readiness Flags, for both the new BAR-OIS (for 2000 & newer vehicles) and the BAR-97 (1999 & older) smog inspections systems. We list the max allowed no ready monitor count below:
What could have caused my vehicle to go into a Not Ready emission monitor mode?
- A common reason which causes emission monitors to become "Not Ready" is having recently disconnected or replaced a vehicle's battery. If for any reason you recently needed to jump start your vehicle due to a weak or defective battery, during the time the vehicle's battery was disconnected or power not provided to the ECU (engine control computer), it is very possible that the emission monitor data previously stored in the ECU was erased.
- If your vehicle's check engine light or service engine soon light is illuminated, the ECU will not be able to conduct the required emission monitor tests, thus rendering any one or more of the monitors Not Ready or Incomplete.
- Using an OBDII scan tool to erase computer trouble codes also causes emission monitors to erase.
What do I need to do to get the OBD II/OBD2 monitors ready?
In order to get your vehicle's emission monitors in ready status, and make the vehicle "ready" for the smog test, you'll need to drive it in a specific driving pattern, known as a "drive cycle". Normally, the required emission monitors should become ready simply by driving the vehicle for 200 to 300 miles and over the course of a few days... without needing to drive a specific pattern. During normal driving the ECU will perform the neccessary internal self-tests required to set the monitors. However, due to individual driving habits and/or patterns, sometimes the drive cycle parameters are not met during ordinary driving, and following a drive cycle specifically designed for your vehicle will be required.
Take extra caution when performing drive cycles on public roadways, obeying all traffic laws. You may also seek repair assistance from your vehicle's authorized dealer. They will be able to complete the drive cycle using manufacturer specific scan tools.
Maximum Number of Not Ready Monitors / Incomplete Monitors Allowed
Gasoline Powered Vehicles:
- 1996-1999 model year vehicles will be allowed one incomplete readiness/emission monitor; any (1) one "not ready" monitor is allowed.
- 2000 and newer model year vehicles will need all emission monitors in READY or COMPLETE status, with the exception of the EVAP monitor. An incomplete evaporative monitor will not cause a smog check failure. It is the only monitor allowed to be incomplete on a 2000 and newer gasoline powered vehicle.
Diesel Powered Vehicles:
- 1998-2006 model year diesel powered vehicles are required to have all monitors complete or ready.
- 2007 and newer model year diesel powered vehicles are allowed only an incomplete exhaust after-treatment system monitor (e.g., particulate filter, NOx/SCR treatment, catalyst, etc.)
