Back in October of 2019, the check engine light came on and my code reader is showing a P0440 and P0456 Evap System with a “very small leak”. 90k miles. My mechanic did a smoke test but found nothing. We reset the code thinking maybe it was just an error. After a week or two, the check engine light came on again. Same code. I decided to do nothing. Now, April 2020, I have 93k miles and if the van sits in the driveway for a couple of days without being started, it takes longer to start. If it sits for over a week, it labors greatly to start. Yesterday, after sitting for two weeks, it took about 10 seconds to start. Obviously, there is a bigger problem now. Yet, the reader still only shows a P0440 as an active code with both the P0440 and P0456 as permanent codes. Any ideas? There are 19 parts related to the Evap system as listed on ProDemand and I don’t want the dealer to rake me over the coals replacing expensive parts.
If you can’t find a leak and the same code returns, there may be a problem with the vapor pressure sensor.
Thanks so much for the info! That sounds like a great idea. I will pass this along to my mechanic as I am taking the van in tomorrow to be re-evaluated.