"George Chandler" > wrote in message
...
> Our 2002 Dodge Grand Caravan is due for NJ State Inspection this
> month, and in keeping with Murphy's legacy, our "check engine" light
> decided to appear a week ago. Using the key on-off sequence, the
> failure code was a P0456, or small evaporative emissions control system
> leak. Researching the situation, I found reports about this occurring
> via a loose fitting or failed gas cap. We have been wanting a locking
> gas cap anyway, so I replaced same, but neither the "check engine" nor
> the P0456 failure code disappeared after several engine cycles. Not
> knowing at this point as to whether the problem had been solved or
> whether the PCM was taking its time resetting, I purchased an Actron
> 9135 scan tool and reset the P0456 failure code.
>
> After resetting the code, four of the I/M parameters went to "NOT
> READY" (CATALYST, EVAP SYS, O2 SENSOR, and HO2 SENSOR). After 50+ miles
> of driving with several engine cold-hot cycles, the "check engine light
> has not reappeared, and three of the above I/M parameters have gone back
> to "READY", but the HO2 SENSOR parameter remains at "NOT READY".
>
> Does anyone have any info as to how long this HO2 SENSOR code will
> take to reset? I have the factory service manual, but can't find any
> info there. If its going to take 30 or 40 engine cycles to reset, I'll
> have to just let the car fail inspection, but would rather not go that
> route if there is anything I can do to get this parameter back in line.
>
> Thanks in advance for any help!
>
>
> George

George, That's why you don't do a battery disconnect or reset the check
engine lite with a scan tool because it will clear all the monitors that
have passed. Each monitor has its own procedures to pass, some actually have
to be driven at a certain speed under a certain load such as the EGR valve
which is one of the hardest monitor to run. I normally advise the cust to
drive it 2 weeks before they bring it back in for a test. It could take more
then 40 cycles or less then 5. It all depends on if the engine is driven as
the PCM monitor is looking for.

More then likely you have a cracked hose under the vehicle next to the
canister or a cracked hose behind the air cleaner housing.

Glenn Beasley
Chrysler Tech