Below was posted on this forum for the C5. Is anyone out there that can confirm it is the same for a C6? I was not aware of this happening when you disconnect the battery until a friend of mine replaced his battery just before getting a NC inspection in which it failed because a battery replacement requires a "driving cycle" before you can check the emissions.... 10 miles, 90 miles.. 10/20 restarts? Not a good thing when your tags expire in just a few days and apparently quite a few "cylces" are required for a vaild test.
Complete the GM drving cycle to reset your C5 computer.
General Motors' OBD-II driving cycle
• Cold Start. In order to be classified as a cold start, the engine coolant temperature must be
below 50°C (122°F) and within 6°C (11°F) of the ambient air temperature at start-up. Do not
leave the key on prior to the cold start or the heated oxygen sensor diagnostic may not run.
• Idle. The engine must be run for two and a half minutes with the air conditioner on and rear
defroster on. The more electrical load you can apply the better. This will test the O2 heater,
Passive Air, Purge "No Flow", Misfire and if closed loop is achieved, Fuel Trim.
• Accelerate. Turn off the air conditioner and all the other loads and apply half throttle until
88km/hr (55mph) is reached. During this time the Misfire, Fuel Trim, and Purge Flow diagnostics
will be performed.
• Hold Steady Speed. Hold a steady speed of 88km/hr (55mph) for 3 minutes. During this time
the O2 response, air Intrusive, EGR, Purge, Misfire, and Fuel Trim diagnostics will be performed.
• Decelerate. Let off the accelerator pedal. Do not shift or touch the brake or clutch. It is important to let the vehicle coast along gradually slowing down to 32km/hr (20 mph). During this time the EGR, Purge and Fuel Trim diagnostics will be performed.
• Accelerate. Accelerate at 3/4 throttle until 88-96 km/hr (55-60mph). This will perform the same
diagnostics as in step 3.
• Hold Steady Speed. Hold a steady speed of 88km/hr (55mph) for five minutes. During this time, in addition to the diagnostics performed in step 4, the catalyst monitor diagnostics will be
performed. If the catalyst is marginal or the battery has been disconnected, it may take 5
complete driving cycles to determine the state of the catalyst.
• Decelerate. This will perform the same diagnostics as in step 5. Again, don't press the clutch or
brakes or shift gears.
Important: Whenever the ignition is turned ON, ignition positive voltage is supplied to the heated oxygen sensor (HO2S) heaters. After verifying the enable criteria, turn OFF the ignition for approximately 5 minutes to allow the sensors to cool before continuing with the test. Once the engine is started, do NOT turn the engine OFF for the remaining portion of the set procedure.
Ensure that the vehicle meets the conditions for a cold start listed above.
¤ If the evaporative emission (EVAP) I/M System Status indicator displays NO, perform the EVAP Service bay test if available.
¤ If the EVAP Service bay test is NOT available, it may take up to 6 drive cycles, with up to 17 hours between drive cycles, for the EVAP I/M System Status indicator to transition to YES.
¤ If the O2S Heater System Status indicator displays NO, ensure that the ignition has been turned OFF for at least 10 hours.
Set the vehicle parking brake and ensure the vehicle is in Park for automatic transmission or Neutral for manual transmission.
Turn OFF all accessories; HVAC system, other electrical loads, including aftermarket/add-on equipment, etc.
Start and idle the engine for at least 2 minutes and until 65°C (149°F) is achieved.
Run the engine for 6.5 minutes within the following conditions:
MAF parameter between 4-30 g/s
Engine speed steady between 1,000-3,000 RPM
Return the engine to idle for 1 minute.
Apply and hold the brake pedal, and shift to Drive for automatic transmission, or apply the clutch pedal for manual transmission and operate the vehicle within the following conditions for 2 minutes:
Depress the accelerator pedal until throttle position (TP) sensor angle is more than 2 percent.
Mass air flow (MAF) signal between 15-30 g/s
RPM steady between 1,200-2,000 RPM
Important: DO NOT touch the accelerator pedal during the idle period. A change in TP sensor angle or an increase in engine speed may invalidate this portion of the test.
Release the accelerator pedal and shift the vehicle to Park for automatic transmission, or Neutral and release the clutch pedal for manual transmission, and allow the engine to idle for 2 minutes.
Quickly depress the accelerator pedal until TP sensor angle is more than 8 percent and return to idle, repeat 3 times.
Allow engine to idle for at least 2 minutes. Caution: Refer to Road Test Caution (See: Service Precautions\Technician Safety Information\Road Test Warning) .
Release the parking brake and drive vehicle at 24 km/h (15 mph) or slower for 2 minutes.
Continue to drive the vehicle for at least 5.5 miles between 45-112 km/h (28-70 mph) with the vehicle reaching at least 80 km/h (50 mph).
Release the accelerator pedal for at least 2 seconds. This will allow the vehicle to enter decel fuel cut-off.
Depress the accelerator pedal until the TP sensor angle is increased 3-20 percent and maintain a safe speed for 1 minute.
Safely stop the vehicle, with the engine in Drive for automatic transmission or in Neutral with the clutch pedal depressed and parking brake applied for manual transmission, idle for 2 minutes.
Shift to Park for automatic and apply the parking brake, or neutral and release clutch pedal for manual. Important: Do NOT disturb the vehicle or turn ON the ignition until told to do so. Disturbing the vehicle may invalidate this portion of the test.
Turn OFF the ignition and exit the vehicle. Do NOT disturb the vehicle for 60 minutes.
Observe the Inspection/Maintenance (I/M) System Status with a scan tool. All of the I/M System Status indicators should display YES.
I have run into this several times on GM and other vehicles... with OBD II, so many things are monitored that a Check Engine Light can be triggered by lots of things... the classic is the loose gas cap... that will throw a CEL and you have to go through more than a few driving cycles before it will clear... if you have a long commute, it can take a quite a few days before you have driven enough 'cycles' to clear the CEL light...
My previous car was a Pontiac Grand Prix and had been sitting in the garage with a dead battery for 3 months. I had the same thing happen when I went to get the smog test. "Not Ready". I drove 10 miles after I left the place, another 5 miles the next morning, took a break and drove another 5 miles and then went back to have it smog tested again. Pass.