Question about Nissan 240SX

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My 89 nissan 240 sx fuel EVAP failed the smog test

I checked the fuel line for any leaks but i cant find any leaks and the hoses looks pretty good

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The carbon canister may saturated. If you are one to try get as much fuel as possible into the fuel tank, that may be how it happened.

Also check the gas cap. There is supposed to be a one way valve to allow air to enter into tank, but not vent out in any direction but by the vent hose to the carbon canister. That valve may be leaking. Also, there is a purge vent to the intake manifold, check to make sure that passage is clear and not carboned up.

Posted on Feb 11, 2012

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Your EVAP system includes all of the connecting EVAP hoses and lines (NOT the fuel lines - you are looking for a vapor leak, not a fuel leak). It also includes the fuel tank, all of the fuel tank grommets and gaskets, charcoal canister, fuel filler tube, fuel cap, purge valve and vent control valve. The failure may be mechanical or electrical in nature. The system needs to be properly diagnosed.

Posted on Feb 11, 2012


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Posted on Jun 06, 2009

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EVAP is evaporative emissions which include the raw fuel vapors from the tank. They are known as hydrocarbons. The evap system contains these vapors and disposes of them through the burning process in the engine. You have valves and solenoids controlled by the computer to purge them from the system. Some of the parts that may cause this test to fail are the vapor lines to and from the tank, the fuel cap (loose or leaking), the carbon canister, and the purge valve or solenoid. It is a somewhat difficult system to test because it is under very low pressure. With all the components in the system, it is hard to say which is at fault. There is a pressure tester provided by Rotunda (Ford service tool) that is made to diagnose this particular problem. You local dealer should have one. About all you can do yourself is visually check the lines and the fuel cap for obvious problems. The MIL light may be on for this reason also. I hope this helps.

Posted on Sep 21, 2009

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1 Answer

My 1985 nissan pickup only failed the fuel EVAP portion of the smog test, how do I fix the problem?

you can fill the system with smoke under pressure to force the smoke out any leaks. you can see if a tool rental shop has a smoke tester you can rent to perform this. do not use any open flame near the system as there are fuel vapours.

Aug 04, 2015 | 1985 Nissan Pickup

1 Answer

Codes p0455

03 VIT
no engine option stated. hard.
0455 is classic EVAP. failure.
99.9% are loose gas cap or bad gas cap.
tighten it, reset the DTC and drive, comes back, then its real.

EVAP is the fuel tanks , venting system. its a Closed system.
the code means it has leak.
in the smog station the first test is the cap is removed
and a pressure test cap inserted on the filler neck. and
we do the classic, leak down rate test.
if it fails you fail.
not surprising, if the cap is tight and new, and you fail evap
we do that test too, first. omg it does leak.
i then hold a 1/2 rubber hose to my ear and find the leak.
we use pressure at 1-2 psi on the filler neck (shop air and reg)
to apply air, and test the system for leaks.
we use dry nitrogen, for safety but if frisky?, real air works too.

if not up to all that, you can inspect every inch of the system
and might find a cracked or hose that fell off the vents.
and friends.

Apr 13, 2014 | 2004 Suzuki Vitara

1 Answer

Code 442-455 replace all hoses coming from the fuel tank, fuel filter and the and some othr that were craked also replaced the gas cap.

old posts.
wow, no year car stated. not that makes this hard....

wow2, no engine option stated,either. trike 2.
did you forget to use the scan tool an RESET the PCM.?
evap failure !
fuel tank , vent failures.
the FSM covers the tests. in detail.

you use pressure tests. we use shop air, and a low pressure regulator (laws in some states require mech to use nitrogen tanks)
we pressurize the vent system. and make sure it works right.
the tests are easy, here.
i most smog stations we do that at the fuel tank filler neck with a cap
adapter to the pressure leak down tester.

Most smog today are from this system failing, that is why each year
the system is more complex.
EVAP 1 ,2, 3, ETC.

there are 3 classes of failure
  1. wont hold pressure (even a bad cap does that)
  2. the solenoid valves bad. stuck etc.
  3. the tests parts are bad, there are parts of this system just to do the test and they too can fail.
all 3 ways and tests are covered in the FSM.
ever seen one, the factory service manual under EVAP chapters.

the PCM does not ever know why or what is bad, it only knows the EVAP monitors failed, nothing more,
a tech, does the EVAP tests by the book and finds , truth.

ill guess year, 2000
read the emissions page here

do you have the leak pump. options?

Feb 26, 2014 | Jeep Grand Cherokee Cars & Trucks

1 Answer

I went to AutoZone and got one of them free check with the code PO456 A Evap system very small leak detected. How do you think I should go about it?

id avoid the zone. but lucky for you, P0xxx codes they can handle.
P1xxx, P2xxx, or more they lie.
99% bad gas cap, or just loose.
tighten the cap, reset the codes, (bingo gone, you and millions of others) use scan tool to reset, or it takes bloody forever ....
if the cap is bad, replace it. if not?
the EVAP tests are complex. no car year stated. sadly.
the first test is the pressure leak down test, got shop Air.
i bet not.
if not, then look for cracked hoses. (fuel vent hoses)
Bty all shops can do the leak down test, and all smog stations
this is the 1st test off the line, EVAP leak down tests.
its a low tech test, easy but most dont even want to try.

here is the 1st google hit,

Oct 02, 2013 | Honda Cars & Trucks

1 Answer

"05 Nissan Pathfinder PO455 EVAP

If those are fuel lines then fuel would be coming out. There are lines that carry fuel vapor for the EVAP system. If these lines you are looking at are the EVAP lines (sounds like they are) then this would be the cause of the large EVAP leak.

Aug 31, 2011 | 2005 Nissan Pathfinder

1 Answer

Mechanic said that there is a small leak in the system according to their computer but was told the leak was too small using a tracer. Any suggestion. They've replaced the gas tank cap but no luck. ...

I assumes, since you mentioned the cap, that you are refering to the Evap System.
There is not much to look at within the Evap System.
Check and make sure someone did not puncture your filler neck to steal gas. That usually gives a large leak but it does not hurt to check.
Also what kind of cap did they replace it with? The Stant locking caps are good for those small leaks. If your area does smog inspections then a smog station may be kind enough to check your cap on their vacuum machine.
Then start at the intake and check the Evap line and follow it to the purge canister and its hoses.

Aug 23, 2011 | 2003 Nissan Frontier Crew Cab

1 Answer

I have a 1999 corolla and it failed e check the codes are po441 and po446 what are these and how can I pass e check? Thanks


Those are EVAP codes - they are emissions related and generally will pose no serious issue to the car. But, in areas that smog cars, having any EVAP codes (CEL for that matter) is an automatic failure.

Most of the time, those codes can be traced back to a purge valve or leaking vacuum lines on the vapor canister (black plastic box underneath the car, right infront of the gas tank. In a few of the cases, the vapor canister is either cracked or completely saturated with fuel. Ususally as a result of topping off the gas tank on fillup (should never top off the tank in this car).

But the EVAP system is fairly complex - those same codes could relate to any leak in the system from the VSV valve under the hood (look for the green cap on a hose, next to the airbox uder the hood) all the way back to the vapor canister and its associated hoses and valves, to the fuel fill line to a cutoff valve on top of the gas tank itself. Easiest way to find a leak is to smoke check the EVAP system - only a shop has the necessary equipment to do that. Due to the specialized equipment and amount of time/effort to diagnose this issue - many times, it is easier to have a shop diagnose the problem, and you can fix it yourself. Valves runs about $50-$75 bucks - hoses are pretty cheap, vapor canister runs from $150-$350, depending on where you get them.

Stay away from any shops that scan the ECM, pull the codes, and say - X component is bad, we need to replace it. You cannot diagnose this sort of problem with a handheld scanner - you need to test the whole system, check every valve, check every hose. Most shops don't like doing the diagnostic work - since it is so labor intensive - they rather just swap parts in, usually at the expense of your wallet.

I hope this helps. Thanks Mike from Fixya

Aug 08, 2011 | 1999 Toyota Corolla

2 Answers

I have changed my fuel cap twice and still my service engine light and check fuel cap light keep coming on what else could it be

Check donut seal where fuel neck meets fuel tank. Possible crack in seal should be visible.

Dec 25, 2010 | 2001 Ford Mustang

1 Answer

I went for a smog test. everything passed but the fuel evap test.

Fortunately, this problem is limited in possible issues. Look at correct and functioning, and tight fuel cap, which is most common issue. There are vent tubes, vapor seperators, charcoal canisters, and purge systems, but they all are pretty rugged and rarely fail...Usually the test centers pressureize the cap and the fuel tank. You really need to know which one failed.

Some test centers only read the computer data, but that should have invoked the indication light, and then you would certainly fail...if you have a check engine light, pull the codes and fix that indication.

Oct 15, 2010 | Ford Tempo Cars & Trucks

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