Timewarpone

I went out of town on a 6 month business trip. My brother-in law was supposed to come by and start the car or drive it once in awhile. Needless to say when I returned the battery was dead. I know I left the car with a full tank of gas but I honestly do not remember topping off the tank. I replaced the battery and all seemed well. I used my Carsoft i980 meter just out of curiosity and everything seems fine. The check engine light never came on. There is something going on with the evap system. The car will not pass smog. Since there are no codes being thrown the exact problem is not being identified. There are no pre-codes lit up just the evap and 2A icons keep flashing. The car performs flawlessly. I have driven the car about 250 miles since replacing the battery. The same 2 icons keep flashing. Earlier today I was putting gas in the car and there seemed to be a back pressure problem. At the pump the nozzle put in only about 3 or 4 gallons. I thought the tank was full but when I got into the vehicle the tank was only 1/2 full. I went on You Tube and saw about 10 videos on evap issues and the general consensus was something related to the charcoal canister?? Does my car, 2005 CLK320 even have one of these and where is it and can it be removed and tested?? or can it be the Fuel Tank Vent Valve ?? I am open for suggestions. No codes are being thrown so I do not know where to start. Thanks in advance.

Rudeney

It's probably failing the smog test because some of the readiness indicators are not set. When you disconnected the battery, the ECU clears all the readiness indicators. You have to drive enough to set them all or else the smog test techs won't pass it. The theory is that even though there are no codes, there "might be" if you drove under different conditions, so the OBDII system has readiness indicators to track driving conditions. Try this:

http://benzbits.com/Drive_Cycle_Readiness.pdf

Timewarpone

Thanks for the drive cycle readiness info. I already was aware of this but not in such detail. About 3-1/2 years ago I replaced the battery and drove it about 150 miles before it passed smog. This time I have driven it over 250 miles and will not pass smog. I will drive it again and again I have until December to officially pass smog. I keep checking for DTC's daily with the battery connected and so far none are thrown. Thanks

Fatz

I believe most scanners will check for the "readiness" status that the emissions testing folks are looking for. There will not be a code, unless something is actually operating out of spec. I am not sure if you can "ready" the car with a scanner....

Timewarpone

So, since there are no codes present then there is really nothing wrong with the car or evap system? I just need to rebuild the memory of the ECU since changing the battery wiped out it's memory. My icarsoft i980 gives the car a clean bill of health my generic OBD2 car reader is the one with the flashing icons (2A & Evap)

Fatz

I think on the generic scanner (I don't recall which one I have) there is essentially a diagnostic selection which checks the car for "readiness". I've never done much with it except check to ensure the cars are "ready" for inspection. They always are, so I've ventured no farther. I've only had the i980 a few weeks and haven't used it beyond making sure it was operational.

Timewarpone

You are right about the OBD2 car reader. I have a bare bones cheapie model that has 3 lights (Red, Yellow & Green) The yellow light comes on with 2 flashing icons Evap & 2A. with No codes thrown. To be sure it was working properly I used it on my 2 other cars and the light was green. My i980 is far superior. I will make a point to drive it every day and check for codes daily. Thanks

Timewarpone

I drove the car today about 60 miles thinking it would clear the last emission indicator 2A (Secondary Air System Monitor). When I checked the car with my OBD2 reader a code was detected PO400 -
Exhaust Gas Recirculation Flow Malfunction. The check engine light never came on and the car drives fine.

Timewarpone

This is strange, this morning I checked if any codes were present. The car is ice cold. I first used my i980 and no codes were present. Then I used my OBD2 car scanner and again, no codes were present and the green light was lit which means it will pass smog. Yesterday I got code PO400 which has something to do with EGR. I will drive it later today and check for codes after it is warm. I am guessing carbon deposits in the EGR valve?? or the vacuum line??? By the way, I never cleared or reset any codes.