2008 Cobalt LS 2.2

I was getting check engine light. Code was for "Coolant". I replaced thermostat and sensor. Unhooked the battery to do repair and clear CEL. All was good afterwards.

Until I went the same day to get a due emission testing.

Failed. Incomplete Monitors. EVAP, OXYGEN,OXYHEAT

I have never heard of such a thing having to wait for it to reset. Is that what I have to do? How long will this take? Is there anyway to clear it myself?

Also, from those 3 things... I didn't cause this to happen with my thermostat replacement did I? Are those codes related?

Im pretty confused and frankly, pissed I have failed! Please help me understand. Thank you.

 

Without a scanner it's hard to monitor if your monitors are set to OK.

Do this roughly

Most OBD II ("On-Board Diagnostics II") diagnostic monitors will run at some time during normal operation of the vehicle. A complete driving cycle should perform diagnostics on all systems. A complete driving cycle can be done in under fifteen minutes.

To perform an OBDII Driving cycle do the following:

1. 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 startup. Do not leave the key on prior to the cold start or the heated oxygen sensor diagnostic may not run.
2. 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.
3. 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.
4. 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.
5. 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 32km/hr (20 mph). During this time the EGR, Purge and Fuel Trim diagnostics will be performed.
6. Accelerate. Accelerate at 3/4 throttle until 88-96 km/hr (55-60mph). This will perform the same diagnostics as in step 3.
7. 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.
8. Decelerate. This will perform the same diagnostics as in step 5. Again, don't press the clutch or brakes or shift gears.

 

The oxygen, oxygen heater and the cat tests will run and complete relatively quickly. The evap test takes the longest. You just have to drive the car around more before taking it in for inspection.

 

Im completely surprised by this. Shows what I know. Would a mechanic tell you not to go get a emission test right after a repair? What about if you get a new battery at the quick lube?.... it seems people would be failing these things left and right!!

FWIW: The EVAP doesn't have to pass in my neck of the woods. Its the other two. I called and asked them to waive it for me but they had none of that.

Does any of those tests (or rather the failure of them at the time of testing) have anything to do with my thermostat and temp sensor replacement? I was moving stuff around in order to get my hands in their deep enough...

 

No necessarily after a repair, more so if you reset the computer by either clearing codes or disconnecting the battery. Soon as it is disconnected and reconnected, the tests run again. If you don't have to pass EVAP, take the car out for a few days and go back. You'll be good.

 

I wouldn't think so. Cat, oxygen and oxygen heater are all exhaust

 

Drove it as normal for a few days and went back and it passed with flying colors.

Still think that is one of the stupidest things I have ever had to deal with in regards to a car. OBD... what a joke.

 

It's not like IL charges for the tests... Some states do, so it could be worse.

If you don't like it, move out of Chicagoland to a county that doesn't test.

 

I don't think I have ever had my evap monitor pass, it always says failed. I replaced everything and it still don't pass. I don't care lol. It works

 

I think in some states, as long as you pass 2 out of the 3 or 3 out of the 4 tests you'll be good. I know here if you don't pass your inspection, they give you a sheet with what is wrong and you have 30 days to fix it and come back and they will finish the inspection for free. So you'll only have to pay the $21