OBD-II Drive Cycle procedure to prep for smog test. (Pass on-board readiness tests)
Courtesy of www.PDXoil.com
For: 1996 and newer vehicles: (OBDII compliant vehicles)
Note: For Oregon DEQ you must have no DTC’S(codes) present.
1996-2000 Vehilcles: These can have two systems unready as long as there have been no previous DTC’s on the unready system detected in a past DEQ test.
2001 & Newer Vehilcles: These can have one system unready as long as ther have been no previous DTC’s on the unready system detected in a past DEQ test.
(It is best to begin with ⅓ to ¾ tank of fuel for EVAP tests to respond more quickly)
1: Cold Start
In order to be detected as a cold start the engine coolant temperature must be below 110°F and within 11°F of the ambient air temperature at engine start.
Note: Do not leave the ignition key on prior to cold start or the oxygen sensor heater tests may not run.
The engine must be run for three minutes with the air conditioner if equipped, headlights and rear defroster turned on. (all electrical loads possible)
Note: Wait one minute before turning on electrical loads after starting engine, the more electrical load you can apply one minute after cold start the better.
This will test the O2 heater, Passive Air, Purge, Misfire and if closed loop is achieved, Fuel Trim.
Turn off the air conditioner and any electrical loads possible and slowly apply throttle until 45-55mph is reached. Release throttle, allow vehicle to slow down then repeat.
Note: Hold throttle steady, during this time the Misfire, Fuel Trim, and Purge Flow diagnostics will be preformed as well as EGR tests.
4. Hold Steady Speed
Hold a steady speed of 45-55 mph for 5 minutes.
During this time the O2 sensor, Catalyst, Air intrusive, EGR, Purge, Misfire and Fuel Trim diagnostics will be preformed.
Note: It is very important that the throttle be held very steady during this time.
Let off the accelerator pedal. Do not shift, touch the brake or clutch. It is important to let the vehicle coast, gradually slowing down to 10mph. During this time the EGR, Purge and Trim diagnostics will be preformed. Catalyst monitors may also run.
Note: Once speed is down to about 10mph apply the brakes as needed. It is best if vehicle is allowed to idle for about 3 minutes once stopped.
Accelerate at ¾ throttle until 45-55mph is reached. This will perform the same tests as in step 3 once more.
7. Hold Steady Speed
Hold a steady speed of 45-55mph for about 5 minutes.
During this time, in addition to the diagnostics performed in step 4, the catalyst monitor diagnostics will be repeated.
If the catalyst is marginal or the battery has been disconnected, it may take several complete driving cycles to determine the state of the catalyst.
Note: Most vehicles are having a problem with the catalyst system if more than two cycles are needed.
This will perform the same tests as in step 5. Again, don’t press the clutch or brakes or shift gears.
Note: Try to let engine idle about three minutes once again
(Drive safely and obey all traffic laws during all phases of testing)