p1456 code a day after filling up

[98civex]

So, I put gas in my 98 civic ex two days ago at a full service station. Drove car on highway a total of 40 mins that same night.

Yesterday driving on highway and check engine light came on. Today went to autozone and had it scanned and got code p1456 Evap system

I took my gas cap off and re-tightened it but the guy at autozone wouldn't clear my code! He said to unplug the battery, I was on a quick break from work so had to get back.

Haven't gotten a chance to clear the code yet but was wondering, if it was a loose gas cap would it have taken a full day to throw the code or just coincidence?

 

[RonJ]

Remove the 7.5A hood Back Up fuse for 3 minutes to clear the code.

 

[98civex]

Ok. Do you know if it was the gas cap being loose, that it would take a whole day to throw the code?

 

[RonJ]

Why ask hypotheticals?

Do this:

Remove the 7.5A hood Back Up fuse for 3 minutes to clear the code.

If the code does not return, then there's nothing to talk about.

 

[98civex]

Why ask hypotheticals?

Do this:



If the code does not return, then there's nothing to talk about.

Hypotheticals help me learn/understand better, but ok will see. Thanks!

 

[lethal6]

Hypotheticals help me learn/understand better, but ok will see. Thanks!

Not if they are wrong. Then all you are learning is that your guessing skills are off.

Troubleshooting is always preferable to guessing. Hypothetical is a good way to waste money throwing parts at problem.

 

[FlatRate]

Most likely its the gas cap since it came on after gassing up. If its old and the O-ring is cracked or if its a non-OEM or just wrong cap it will throw the code. The code is for gas tank side of EVAP system.

If that checks out good then its usually the By-Pass Solenoid Valve and the 2 Way Valve that fails when the code repeatedly returns. What happens is it is filled with fluid from the gas tank. If you read carefully at the pumps, you are not suppose to top off. And if its full service you may have that scenario.

What you do is lift car up and take the 2 way valve apart from the system. Or if you can tilt it enough to see if fluid comes out of it when you disconnect the 2 hoses from it. If you see fluid then thats is where the problem is. Since the 2 way valve is mounted to the by-pass solenoid, it is advised to replace both.

 

[98civex]

The code returned last night when I drove a total of 40 miles on the highway but all week city driving there was no check engine light.

First time light came on was on the highway too. I haven't topped off in a while when gasing up.

Should I just replace the gas cap first?

 

[RonJ]

Should I just replace the gas cap first?

Because it's cheap, give it a try, and then cross your fingers.

 

[98civex]

Will do. Till I get a new one, is it bad at all for the car to drive around or is it just an emissions issue?

 

[RonJ]

Will do. Till I get a new one, is it bad at all for the car to drive around or is it just an emissions issue?

Just emissions

 

[98civex]

Changed the cap with an oem Honda replacement. Reset the ecu, and again the check engine light came back on while highway driving.

It's a little frustrating that it seems to take 50 miles of driving before the light comes on. Prolongs the troubleshooting process.

 

[nhoz22]

Replace the 2 way valve.

Sent from my SGH-T999 using Tapatalk

 

[98civex]

Replace the 2 way valve.

Sent from my SGH-T999 using Tapatalk

Are you sure?

 

[98civex]

http://bit.ly/17fJHQZ
Is this it?

 

[98civex]

I called Honda asking for a price for a two-way valve/bypass solenoid and here's what he said:

"For your car there's a three way valve and a shut off valve. The culprit is most likely the shut off valve and it's $159"

Now I'm confused. Is shut off valve same as what everyone is suggesting on here?

 

[98civex]

So I got the parts recommended to fix sorted out: two way valve and bypass solenoid by driver's side fuel tank

When replacing I noticed a hose coming from an inlet from the chassis that went into a T connector which connected to a smaller hose going into the fuel tank pressure sensor. This is not the same hose that attached to the bypass solenoid but a smaller one right next to it. Anyway that hose was snapped off and the T connector was just barely hanging from the sensor.

Replaced the hoses as well but here's my question, I presume that's for fresh air since the end of the T didn't seem to connect anywhere else. What purpose do the hoses and connector serve? Couldn't that port in the sensor just be left open as it'd still be exposed to fresh air?

 

[RonJ]

Click site 1 in my signature and download the 96-00 Civic manual.

Fuel & Emissions > Emission Control System > Evaporative Emissions Control

If an EVAP system hose was disconnected and open to the air, then you found the problem (return the valve).

 

[98civex]

Click site 1 in my signature and download the 96-00 Civic manual.

Fuel & Emissions > Emission Control System > Evaporative Emissions Control

If an EVAP system hose was disconnected and open to the air, then you found the problem (return the valve).

But that hose I'm referring to doesn't go into anything I checked. It looks like it's there just to get fresh air to the fuel tank pressure sensor.

Here's a quick drawing illustrating it:

 

[RonJ]

Click site 1 in my signature and download the 96-00 Civic manual.

Fuel & Emissions > Emission Control System > Evaporative Emissions Control

If an EVAP system hose was disconnected and open to the air, then you found the problem (return the valve).