Hey guys,

The Service Engine Soon light came on today on my car, so I checked the codes. Here's what I pulled --

0903 -- EVAP Canister Vent Control Valve
0705 -- EVAP Control System
0304 -- Knock Sensor

I'm sure the Knock Sensor code threw because of the EVAP system, and I'm sure the EVAP system code threw because of the Vent Control Valve. I'm going to order a replacement valve to fix the problem.

My question is, could the valve be causing my car to hesitate before starting? Lately I've been having this hesitation, so I've been concerned. I'm hoping the EVAP valve will fix it.

Does anyone have any input?

Thanks,
-Nick

 

try to clean your canister... usually its because there is some gunk stuck in it ...

 

Where do I clean though? I guess I'll just have to take it all apart and clean it out. Looks like the car is gonna sit until I have a chance to clean it.

I really want to know if this is causing my starting problem though. Sometimes the car doesn't sound like it's going to start. I don't want to get stuck somewhere when the car doesn't start. It almost sounds like I have a dead battery, but it's not dead because I can turn the radio on and stuff when the car is off, and the lights work and everything.

-Nick

 

clean the valve by taking it off the front of the cylinder.. i had the same problem with hard starts. I also changed my fuel filter and my battery at the same time that I cleaned the valve too, so I'm not exactly sure what was causing the starting problems..

 

What's got me swinging is how does anybody know that EVAP control vent closed means something needs to be cleaned? I followed the advice of the forum and wasted my time taking the cover off, then removing the assembly and these tiny tubes and tried to clean. The dealership told me there is a "diaphragm" that is blown when the service engine soon lamp comes on, and the assm. needs to be replaced. It cost over $400, yes, but after the service was performed, the car went back to running normally. Prior it would not start on the first try, bucked when accelerating, and when over 90 F outside it took 3-5 cranks to start. In retrospect I woulda rather spent the $400 and had it done right than to lift my car, remove the rear-left rim, deal with rusted bolts, and try to clean something that was broken to begin with! I like to save money just like the next guy, but I do not like to spend my time trying to fix something that is beyond repair. If somebody knows how to replace the entire assy then fine, post the directions. just my .02

 

Where's Tom at? He is usually all over these threads.

 

Where is the EVAP canister located?

 

next to the driver's side rear wheel

 

The Evap canister is near the gas tank under the car.

The reason it threw the EVAP canister code is because of the EVAP canister control valve.
I had this code pop up on both of my 4th gens when i bought them and i never found any way that it would affect emissions or the way the car runs. :dunno:

Basically, if you clean the canister valve, (take it apart, spray some WD-40 in there ) it will get rid of both codes related to the EVAP system. But I can't help you with the Knock Sensor as mine popped up recently as well, together with the Air temp sensor.

You may very well be needing a new knock sensor.

btw, here is a pic of the valve as i remember:


the white thing is the vent control valve.

 

Frank - Sorry you had a bad experiance while being the DIY mechanic. There's always the possibility that you wount fix it. 90% of the time a cleaning of that valve brings the EVAP system back to working order. Unfortunately you were not among that 90%. At leaset you gave it a try and learned something. Even though it cost you $400 bucks, you learned something from hands on experiance, and that is priceless.

 

Thanks guys. I took the valve off and sprayed some WD-40 in there. The EVAP system is back in working order (at least the light hasn't come back on yet). As for my car not starting, well that's another story.

-Nick

 

I had the same experience--the first time the light was off for weeks. I repeated the procedure, but the light turned on 2 days later. The 3rd time, I would reset the lamp but it turned on minutes later. That's why I finally went to the dealer. Obviously a 4th gen Maxima should start the 1st try, whether the motor is cold or hot, and no matter what the weather is. I knew my car wasn't running right and it's a bit weird taking 4 tries to start a car like a Max.

My hunch is that people are reluctant to change the boost sensor (25085-2L900) because that's not cheap, it lists for about $150. The valve assy. and canister are cheap, about $40 and $46 respectively. Good luck. Again, I prefer to have the car run properly, but if you just want the light off the cleaning could work.

 

could you explain to me where the boost sensor is?

my evap system has been throwing codes for god knows how long now... plus i popped off the valve on the side of the evap box and cleaned it and the light still came back.

thanks,
Ant