I have an evap system issue with a check engine light cod...

Q: I have an evap system issue with a check engine light code P0456 for a "really small leak"

asked by on July 07, 2017

I need help diagnosing a P0456 evap system code for a "really small leak" so far, I have changed the purge valve and gas cap and neither of those worked because the light came back on. I took it to get smoke tested but they found no leaks. So now I don't know what to do thanks! If it helps, I do sometimes notice that my RPMs are pretty high on the freeway, at around 4K going 75-80 miles an hour which seems quite excessive to me, but I don't remember if that's how inefficient my car has always been before this issue.

My car has 128500 miles.
My car has an automatic transmission.

Hi there. Unless you have professional EVAP system leak detection equipment, there really isn’t much more you can do to isolate or diagnose the source of your EVAP leak or warning light. The one thing we can suggest is to read this article on the P0456 OBD-II trouble code to review all possible sources and repair suggestions.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

BRAKE FLUID LEAK; REAR DRIVER SIDE 2005 Chevrolet Cavalier

Hi - the brake fluid leak you discovered could be a damaged brake line, or leaking brake caliper or wheel cylinder. I recommend a brake system inspection ASAP, performed by a mobile, professional mechanic, such as one from YourMechanic, who...

Car stalling and jumping.

This car has a transmission that has solenoids that control the shifting and sometimes the solenoids or speed sensor causes erratic shifting. The vehicle would have to be tested to see what codes are in the computer and diagnose the...

Kill switch won't let me start car

Dealing with a troublesome alarm can be frustrating. Ultimately I would recommend purchasing a new remote key fob and having it programmed to your vehicle so you can have use of your alarm system. Until you are able to do...

Related articles

A Buyer’s Guide to the 2012 Mazda 6
The The Mazda 6 is a luxurious alternative to the everyday family sedan. It has decent fuel economy with an upscale look on both the inside and the outside. The vehicle also handles well on the highway and is comfortable...
The Best Used Cars to Buy for Highway Driving
Do Do you spend hours each week on the highway for work? Maybe you just live in a very rural area and have to drive for 30 or 45 minutes to get to the grocery store. Whatever the case, your...
The Best Used Cars to Buy If You’re an Architect
Obviously, Obviously, architects appreciate beauty and symmetry. This is not just the case when it comes to their building projects, but also in terms of the vehicles they choose. We have evaluated several used cars, and identified the Mercedes...