I went to a local part store (auto zone) and had my 99 accord v6 tested because the check engine light was on. It returned with the code P1456. Can someone tell me what this code mean? They were ablet to give me the code but not able to tell me what it mean because something was going on with the system thanks for your help in adavance.

 

It's good that you had the code it helps. It means...

Evaporative Emission Control Sstem Leak Detected (very small leak)
This is what it says from the book.

 

P1456 is a leak in the gas tank or related system. This is the code you'd get if you left the gas cap loose. But if you're sure you didn't leave the gas cap loose, there's a few other things...

Basically, the gas tank isn't airtight like it should be. The gas cap might have a bad gasket so it leaks even after you tighten it.

There's several smaller hoses & a valve associated with the gas filler neck. Look for loose hose clamps or something out of place. I think you remove a cover inside the wheel house, to see that stuff.

Maybe the bolted flange on top of the gas tank, for the fuel pump. Check for loose or bad gasket.

Several hoses associated with the EVAP canister, which lives about underneath the left-rear seat bottom. But most of that system would throw P1457 instead.

It's possible there's a leak in the gas tank, up high so liquid doesn't leak. But I imagine you'd smell the gasoline vapors leaking??

Finally, there's a pressure sensor on top of the gas tank, which the ECU uses to decide whether the tank is airtight. That could be bad.

The Helm repair book has a really nice comprehensive set of tests for this code, but it takes several pages & I'm not going to try to repeat it from memory...

 

That sounds like it could be a nighmare to locate and fix that problem. Maybe it is possible to temporarily defeat the pressure sensor to see if that itself is the problem.

 

If you defeat the sensor you haven't really shown that it's a bad sensor vs. an actual leak.

The procedure has a lot of tests with a MityVac to see whether each solenoid valve holds vacuum or leaks. You may find a disconnected vacuum hose as the problem. The tests aren't real difficult until you get to the point of checking the sensor (drop the gas tank)...

 

My advice would be to make sure the gas cap is tight, Clear the light and see if it comes back. Oh, and dont overfill the gas tank.

 

chances are that it's a problem with gas cap, make sure when you put on the gas cap that it has the rubber gasket in there and then tighten it down and make sure it clicks a few times, then reset the code (autozone should do this again) and see if that fixes it

 

I have checked the gas cap and made sure it was tight and had the CEL reset. I will see if the light comes back on. Thanks for all the help.

 

at least you didnt get one of the "12" codes (EGR valve ineifficient flow) because that is quite an involved fix if your car is past the 8 year 80K emissions warranty

 

if lite comes on again same code,,,,,,,,,,before doing anything,, replace the gas cap ( Honda part) , reset the ecu and drive the car ..

if it comes back on again then you need to have the evap system tested,,,,,,
what i have found bad on some of these cars causing also code p1457.. is the evap 2 way valve and the evap bypass solenoid valve

and like Chio said DO NOT overfill the tank..