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Trouble code p1494

ohTONYoh

Proven Member
173
6
Jul 29, 2012
yorktown, Virginia
My check engine light came on as soon as i started my car this morning. Went to autozone and they tested it, it came out as:

EVAP ventilation switch or mechanical fault.
Probable causes:
-Open or short circuit condition
-Poor electrical connection
-Failed vent solenoid
-Vacuum hose plugged

Im not sure what EVAP is, and i dont know what part the above problems are stated towards. I HAVE searched but none of the threads on this were finished and didnt completely help in the first place.Plus they are at least 6 years old.

I guess i need to know what direction to look in for problems, help would be very appreciated.
 

scottinaz

Probationary Member
4
1
Nov 5, 2012
queen creek, Arizona
the evap system is the air that collects inside the gas tank. it gets recirculated and burned in the motor instead of being vented to the outside air. there is a solenoid that opens and allows the tank vapor to be diverted to the intake manifold and burned. there will be a solenoid with an electrical connector (usually 2 wire) with 2 vacuum hoses, one goes to the intake manifold. the other will go to a hard metal pipe that goes under the car to the tank. it usually runs net to the fuel lines. that solenoid may be bad or unplugged.
 

bullettdsm

N/T DSM Wiseman
DSM Wiseman
2,609
34
Dec 17, 2004
East Hampton, Connecticut
This could be a scary one. Guys have literally walked away from their cars because they could not get rid of this code.

Now with that scary thought in you head, you have a strategy. What is going on is you simply have a vac leak somewhere in your evap system. In your engine bay is a schematic of the evap system to follow. That will help you check hoses etc.

BUT you should start of simple first; Gas cap. A loose or broken/defective gas cap can throw this code. You can have a place check it (I'm thinking that Advanced or Autozone can do it for you. Or a local garage may be able to) but I just use a known good cap (I have many in my garage). You can simply buy on for as cheap as they are, or you could borrow a known good from another car.

If its not the gas cap, then start looking at vac lines. Did you do anything recently in the engine bay that may have broken, or knocked off a line? A visual inspection would br warrented here. If you found nothing there, then you would have to start checking for leaks. But before you did that you may want to do a visual check at the ldp to see if the plug got knocked off or something.

MB
 

ohTONYoh

Proven Member
173
6
Jul 29, 2012
yorktown, Virginia
Havnt done any mods or anything to knock a hose or something loose.

Checked the LDP and disonnected the connector, service engine still on.

But, the light would go off when im driving sometimes, then come back on a little later. Its been off for 2 or 3 days (knock on wood) now so im hoping it was just a loose something.
 

Th3DooM

Proven Member
301
3
Jan 5, 2011
Dresden, Europe
About a month ago I got exactly the same code as OP. I left the car at the dealership because I wanted to get my windshield and rust fixed. After 7 days I got it back and when I started it threw the P1494 code immediately. I have to say that the fuel level was very low. 2 weeks after that I just deleted the code and it never came back.

I know they had to disassable the whole upper interior, but how can the EVAP-system be touched? I visually checked some hoses and parts of the EVAP-system when I was under the car but found nothing.
 

ohTONYoh

Proven Member
173
6
Jul 29, 2012
yorktown, Virginia
About a month ago I got exactly the same code as OP. I left the car at the dealership because I wanted to get my windshield and rust fixed. After 7 days I got it back and when I started it threw the P1494 code immediately. I have to say that the fuel level was very low. 2 weeks after that I just deleted the code and it never came back.

I know they had to disassable the whole upper interior, but how can the EVAP-system be touched? I visually checked some hoses and parts of the EVAP-system when I was under the car but found nothing.

It has to do with cold starts. Im thinking the heat made the gas evaporate more and faster. My code came up when it first started getting cold for maybe 4 days, then went off and never came back. :applause:
 
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