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Check engine light = automatic smog check fail?

S

SuperTool

Lifer
I have a CEL having to do with EVAP canister purge volume control valve.
This does not effect tailpipe emissions, so why does the state of CA care?
 
There is nothing wrong with the car. I've been driving with that check engine light for months now, and it performs as well, gets the same mileage, and has same tailpipe emissions. I can hold my hand to the tailpipe, and then lick it, and it's pure water on my hand.
 
Originally posted by: SuperTool
There is nothing wrong with the car. I've been driving with that check engine light for months now, and it performs as well, gets the same mileage, and has same tailpipe emissions. I can hold my hand to the tailpipe, and then lick it, and it's pure water on my hand.
Click to expand...

Well that is certainly an interesting interpretation of an emissions inspection.

However, the whole point of the "EVAP" system is that it prevents gas fumes from entering the atmosphere. So it is reasonable that a failure in this system would fail your car.

It shouldn't be hard or expensive to diagnose/repair one of those codes, unless it is some completely off the wall problem.
 
Originally posted by: flot
Originally posted by: SuperTool
There is nothing wrong with the car. I've been driving with that check engine light for months now, and it performs as well, gets the same mileage, and has same tailpipe emissions. I can hold my hand to the tailpipe, and then lick it, and it's pure water on my hand.
Click to expand...

Well that is certainly an interesting interpretation of an emissions inspection.

However, the whole point of the "EVAP" system is that it prevents gas fumes from entering the atmosphere. So it is reasonable that a failure in this system would fail your car.

It shouldn't be hard or expensive to diagnose/repair one of those codes, unless it is some completely off the wall problem.
Click to expand...

Well, I did diagnose it, which is how I know what the problem is. It's a common problem, because Nissan exposed that valve to dust and dirt, so it gets clogged easily. I had it before and I sprayed some WD40 in there and it worked fine for another 30K miles. Now it's back again, and WD40 didn't work 🙁
 
The evap system is to remove raw fuel vapor from the fuel tank. It is emmissions related but will most
likely not affect the way the car drives unless it causes a vacuum leak, some are vacuum operated.

The reason California cares is because of the fuel vapor in the atmosphere. You know those caps on
tops of the nozzle you fill your tank up with? They're there for the same reason, to capture the
fuel vapor before it reaches the atmosphere.


DD
 
But that valve is not there to prevent leaks. It's my understanding that it's there to seal the canister to test for its integrity. So as long as there is no problem with the canister, it's not a problem.
 
Yes, you will fail. The CEL enough will cause a failure even if the tailpipe tests are satisfactory. Replace the part. The entire purpose of ECUs and CELs in cars is to monitor emissions. In fact, a car's ECU is considered to be a major emmissions control component and as such is covered under the federally-mandated 8/80 warranty.
 
Originally posted by: SuperTool
But that valve is not there to prevent leaks. It's my understanding that it's there to seal the canister to test for its integrity. So as long as there is no problem with the canister, it's not a problem.
Click to expand...

The evap system on modern cars tests itself at different intervals by pulling a vacuum on the
evap system and seeing how well it holds that vacuum. If the vacuum leaks for any reason, an engine
code gets set. If that valve isn't operating properly, the system can't test itself for leaks and so it
sets the code that the valve has failed.

EDIT: It tests the whole system, not just the canister.

DD
 
OK, It looks like I've been spraying WD40 into the wrong valve, evap canister vent control valve. That's the one that failed last time.
The one failing now is the evap canister purge volume control valve. Does anyone know where it is on the 1996 Maxima.
 
Originally posted by: homestarmy
Just reset your ecu right before they inspect your car...
Click to expand...

That won't work. A just reset ECU won't connect to the smog check station computers unless it has " re learned" everything. Trust me on this...I had to drive my car 30 miles after I changed the knock sensor to do the smog check again.
 
Man, I'd be screwed. My car's electrical system is messed up; the CEL comes on randomly, as does the ABS Failure light. (Which I find amusing when I can feel the ABS kicking in) Sometimes the CEL comes on to indicate that computerized fuel injection regulation is no longer working, usually because the car has been driving on the highway for a few hours. This doesn't affect emissions or anything else, except for my fuel economy which drops to roughly 8 miles/gallon while the light is on. I can't exactly fix the problem either: my mechanic tells me that the electrical system is screwed up pretty much from step to sternum and that fixing it would require rewiring the entire car. The end cost would be roughly $1100 in estimation. (No, my mechanic isn't trying to screw me either; he's a friend) Fixing it, he says, isn't worth the slight benifits that would come with it.

Still, that damn CEL -- in this case not even related to smog -- would keep my car from passing. Bleah.
 
So I fixed the problem 🙂
Gonna get it smogged tomorrow. The stealership wanted $220 for the valve. I got it from a dismantler for $40 using copartfinder. Took 10 mins to swap the valves, and reset the ECU. 😀
 
A CEL will not cause your car to fail the emission test, My wifes car has had the CEL on for a couple of years now, it is an egr flow too low code, but it does not affect the emissions at the tail pipe so it did not fail.
 
Originally posted by: SuperTool
Maybe the law is different in CA.
Click to expand...

It is different in every state. Here, if the CEL is inactive, and there are no stored codes relating to emissions, you pass instantly. If your CEL is on, you have to go through the tailpipe and vacuum tests.
 
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