Code p1491
#1
Code p1491
My wife's 03 Maxima just popped the service engine light. Came up with code p1491 EVAP vacuum cut valve/bypass circut malfunction. Does anyone have a good suggestion as to where to begin looking to diagnose/fix the problem. My first real dealing with the Nissan. Will take any help I can get. Thank you...
#2
My wife's 03 Maxima just popped the service engine light. Came up with code p1491 EVAP vacuum cut valve/bypass circut malfunction. Does anyone have a good suggestion as to where to begin looking to diagnose/fix the problem. My first real dealing with the Nissan. Will take any help I can get. Thank you...
- Vacuum cut valve bypass valve
- Vacuum cut valve
- Bypass hoses for clogging
- EVAP control system pressure sensor and circuit
- EVAP canister vent control valve
- Hose between fuel tank and vacuum cut valve clogged
- Hose between vacuum cut valve and EVAP canister clogged
- EVAP canister
- EVAP purge port of fuel tank for clogging
I would start by checking the hoses. Re. the FSM, you can get it from here: http://boredmder.com/FSMs/Nissan/Maxima/
Last edited by maxiiiboy; 01-05-2015 at 01:58 PM.
#4
In the EC file search for your code p1491... Takes you to page EC-598.. Try out the testing without a CONSULT-II
Some of the parts are located underneath the car near the rear driver side area...
Last edited by george__; 01-05-2015 at 05:48 PM.
#5
My wife's 03 Maxima just popped the service engine light. Came up with code p1491 EVAP vacuum cut valve/bypass circut malfunction. Does anyone have a good suggestion as to where to begin looking to diagnose/fix the problem. My first real dealing with the Nissan. Will take any help I can get. Thank you...
Another option would be to spray / cycle with valve in place. This would spare you trouble of dealing with those M6 (10 mm head) bolts holding canister in place. Due to rust I broke 3 of them holding canister to its bracket and then other 3- holding bracket to the body. I had to drill out the remainings and re- cut the threads, not fun. 2 other bolts holding valve to the canister also broke, the canister's plastic around one of them was cracked too. I epoxied cracks, re- cut the threads and all is well since then .
New canister costs ridiculous money and it's nothing more than plastic box with charcoal inside, it doesn't go bad. It is one of few places in the car where I consider 'ghetto approach' to repair acceptable.
Last edited by Max_5gen; 01-06-2015 at 12:06 AM.
#6
^Sometimes they do go bad by the charcoal getting loose and clogging up the lines making you have to replace the unit and blow out your evap lines with compressed air to get the charcoal out. Sad, but true.
#7
Start by checking the hoses as Maxiiiboy said. They could be getting stiff and brittle, which makes them crack and leak.
Next step would be to remove the wire harness connector and check the coil of the valve resistance. I don't know what the resistance reading should be, but in general these things should be in the 20 to 50 ohm range. If the resistance reading is real high, then it is bad.
Then see if the valve is getting the voltage to operate. Follow the FSM for how to do this.
Next step would be to remove the wire harness connector and check the coil of the valve resistance. I don't know what the resistance reading should be, but in general these things should be in the 20 to 50 ohm range. If the resistance reading is real high, then it is bad.
Then see if the valve is getting the voltage to operate. Follow the FSM for how to do this.
#8
Start by checking the hoses as Maxiiiboy said. They could be getting stiff and brittle, which makes them crack and leak.
Next step would be to remove the wire harness connector and check the coil of the valve resistance. I don't know what the resistance reading should be, but in general these things should be in the 20 to 50 ohm range. If the resistance reading is real high, then it is bad.
Then see if the valve is getting the voltage to operate. Follow the FSM for how to do this.
Next step would be to remove the wire harness connector and check the coil of the valve resistance. I don't know what the resistance reading should be, but in general these things should be in the 20 to 50 ohm range. If the resistance reading is real high, then it is bad.
Then see if the valve is getting the voltage to operate. Follow the FSM for how to do this.
I have never heard of the charcoal clogging the EVAP lines in Maximas and creating problems. I don't actually see why clogged EVAP line would be a problem or how this could even happen- there's not much flow there to suck something in. Usually EVAP system fails the vacuum test regularly performed by ECU and that place is famous for causing this.
Last edited by Max_5gen; 01-06-2015 at 09:21 AM.
#11
I have never heard of the charcoal clogging the EVAP lines in Maximas and creating problems. I don't actually see why clogged EVAP line would be a problem or how this could even happen- there's not much flow there to suck something in. Usually EVAP system fails the vacuum test regularly performed by ECU and that place is famous for causing this.
https://maxima.org/forums/4th-genera...-charcoal.html
I'm not seeing any threads on this in the 5th gen section.
Must have been a defect in 4th after it gets real old or just no one has noticed it for the 5th yet.
Last edited by Fakie J Farkerton; 01-06-2015 at 12:03 PM.
#13
No, nothing will happen in months, let alone days. The only unpleasant side effect is SES light which you have to live with and inability to see if other unrelated problems happen to trigger the light later on since it will be already lit for this reason. Good OBD reader will pull all the codes though.
#16
IMO EVAP system prevents gasoline vapors from escaping into atmosphere. It has to maintain negative pressure so in case of small leaks it would suck in air instead of releasing gasoline vapors. I'm not sure about fuel consumption as well- it's not part of fuel ratio loop but I might be missing some indirect effect here. In any event it would be much less noticeable compare to failed O2 sensor or to short daily commute pattern for example.
Last edited by Max_5gen; 01-06-2015 at 08:42 PM.
#17
You might want to soak those bolts WD40/Liquid Wrench/PB Bluster meanwhile. Didn't work for me though after 2 days and around 70 degrees temp: the car smelled like Liquid Wrench itself, everything there was dripping it and I still couldn't unscrew even single one of them. If someone knows how to tame those suckers please share the experience as heating them is out of question due to proximity of gasoline vapors.
Last edited by Max_5gen; 01-06-2015 at 08:41 PM.
#18
As annoying as a couple of things have been on this car. Using fire to remove bolts is starting to sound like fun. Its just had some issues (none super major). But, annoying. Good thing for it, that my wife loves it.
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Kyle Lee Cleveland
6th Generation Maxima (2004-2008)
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09-28-2015 09:01 PM