ChodeMcblob

Hi

I have a 2002 C5 Convertible with 23,000 miles.
I recently found my battery dead and had to recharge it after that I had to take it for State emissions testing.

The car failed twice because when the car was on the OBD II scanner it was showing that the cat sensor was not ready nor was the secondary air system.

Correct me if I am wrong but a C5 doesn't have a secondary air system. When I went to Chevy they said that because the computer was cleared because of the dead battery the only way to get the cat sensor to kick on was to go through many drive cycles.

Well I did what they said and still nothing. The car is bone stock with no mods and has always passed inspection. Any thoughts out there?
Thanks

vettenuts

The not ready's indicate that the test in question hasn't taken place within the PCM and been passed. Some of these tests have very particular driving sequences required for them to take place. There was a GM driving sequence around on there somewhere that specified how to drive the car to try and get all emission system tests to take place, not sure where it is. C5 does have a secondary AIR system, you can see one of the check valves on the driver's side exhaust.

Patches

I had reloaded a previous tune in my C5 with EFI Live when I moved up here to Indiana and then had to have the emissions test. I used EFI Live to check the emissions status and it indicated I would not pass so I drove most of the GM OBDII driving cuycle below, pulled over and checked the status and it had enough to pass so I drove straight to the emissions station, had it test and passed. They no longer check emissions here.


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.