I own a 2005 Winnebago with a dead engine battery. It also needs a smog check soon. I asked a mechanic if he could do both at once and he said no, because after he replaced the battery, I would have to drive it 100 miles before he could successfully do a smog check. I never heard of such a thing. Is he right?
Jim Campbell
San Jose
Yes, he is right. You need to get some drive cycles in place before the computer is emissions ready after disconnecting the battery. More of a concern for an RV that sits vs cars driven every day.
GM (Chevy, Buick, Cadillac, GMC, Pontiac, Oldsmobile): Drive Cycles are not included in the
manufacturer’s public web site or owner’s manual. The following drive cycle is from
http://www.obdii.com/drivecycle.html:
To perform an OBDII Driving cycle, do the following:
- Cold Start. In order to be classified as a cold start the engine coolant temperature must be
below 122°F and within 11°F of the ambient air temperature at startup. 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
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 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, touch the brake or clutch. It is important
to let the vehicle coast along gradually slowing down to 20 mph. During this time the EGR, purge
and fuel trim diagnostics will be performed. - Accelerate. Accelerate at 3/4 throttle until 55-60mph. This will perform the same diagnostics as
in step 3. - Hold Steady Speed. Hold a steady speed of 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.
It was true for our Honda Fit when we had work done and then needed a sticker.