Good Morning Folks,

You may remember a couple months ago I posted a thread about my '97 Dodge Ram getting a Engine Check light which turned out to be a P0411 code. At that time it was the 4th time it happened to 12 yr old truck. Well I just got another last night. Really irksome because I truly thought the problem was me..... that is I was really tightening the gas cap properly. I guess that's not the case because I'm 4 or 5 clicks on the cap now. I'm heading for Napa or Autozone this morning to get the code read, but I'm sure it will turn out to be another P0411.

As I mentioned in my earlier threads I haven't experienced any performance problems and no lower MPG other than what this extremely cold weather is causing. I'm been sippin' coffee this morning and googling "P0411". I found LOTS of hits. I found this one which I will copy and paste which says gas mileage will suffer big time if you get a P0411 code. It doesn't seem to be the case for me... but I am paying closer attention now.

So gurus what is your opinion on the gas mileage part?

Here the copy and paste.....

p0411 is a generic code, probably a vacume leak,vacume hose broken check this first, check the air pump turn on the car but it needs to be cold, you should hear a high pitched whine, this is the air pump running,there are 2 hoses one suction one blowing thishose should be going from the air pump to the air cleaner disconnect that and see what the volume is should be pretty strong.
But mostly you probably have a broken vacume line somewhere
This a pretty vague question. I'll assume you have a "Check Engine" lite on and that's the fault code? If so, the secondary air injection system generally uses an air pump and two steel lines. One goes to the Exhaust Manifold(s), and the other to the Catalytic Converter. An electronic solenoid, controlled by the engine computer, switches the air "upstream" when cold, and "downstream" when hot. When the engine is cold, it doesn't use the Oxygen sensor and pumps extra air into the exhaust manifold(s) to help reduce emissions. When the engine warms up, and the oxygen sensor is in operation, the computer switches the air pumps' air downstream of the oxygen sensor, to the catalytic converter. The extra air in the converter helps it to convert harmful emissions to CO2 and H2O. If there is a malfunction in the system, it could pump air upstream with a warm engine, and all that extra air would cause the oxygen sensor to go full lean. Then the engine controller would dump as much fuel as it could into the engine, and emissions would skyrocket, and fuel mileage would suffer drastically. If it pumped air downstream all the time, cold engine emissions would suffer. I hope I have explained this so you understand what the system is for, and it's importance of keeping emissions down.

BTW, I still have not replaced the original gas cap but plan to do that this morning...

Thought I would throw this is also... I drove about 250 miles on a day trip yesterday. My starting elevation was slightly under 5000 feet and I climbed to around 11,000 ft (6000 ft gain).... then return to the lower level. The engine check light came on at the end of the trip. Could that change in pressure cause any problem? Sort of a dumb question.... but those of you who live in the mountains know what happens to a bag of chips.. when you gain 6000 ft or so.... (the bag looks like it's going to burst).lolol


Any thoughts would be greatly appreciated.

Thanks....... and sorry for being so "wordy".....
Jason.....

 

are you sure its a 411 or could it be a 441 ?

i got a P0441 several months ago. i looked at the gas cap and oiled the o-ring/gasket and blew through the check valve. reset pcm. cel came back.

i checked the vac lines around the evap canister and evap purge solenoid and they 'looked' ok. i wiggled them and made sure they were tight. reset pcm. cel came back.

the evap purge solenoid is a tad expensive at $40. and a gas cap is only about $12.

as an experiment i placed a thick, quart size plastic zip lock bag over the cap gap and put it back on. reset pcm. the point was to seal the cap and verify the problem was just the cap and not something else. so far its been about 3 or 4 weeks and 2 or 3 tanks of gas and the cel/P0441 has not come back. so that pretty much confirms its just the cap for me. probably the check valve in the center of the cap leaking. if you do something like this take care not to get any debris in the tank.


http://www.autozone.com/autozone/cat...&parentId=60-0


by the way - i just noticed. on the inside of the fuel door is a hook that perfectly holds the gas cap while you're refueling. i'm impressed.

also by the way, the Stant brand replacement cap does not come with the tether. i think you could drill a hole and reuse the old tether. i wonder if a dealer cap would come with a new tether and how much that might cost ?

 

My mistake...... it is a p0441.... Guess it was too early when I posted....

I'm off to have Autozone read the current one on their monitor. BTW, I called Napa and they told me they don't do that. They do have monitors for around $150.....

I'll post back with today's reading... Thanks dhvaughan.....

Jason

 

Just got back from Autozone.......The monitor showed the code to be P0441...... just like all the others.

And I bought a new gas cap. The Autozone guy told me the light would probably go off in the next 3-4 days. Does that make sense?

That is if your correct a condition on a '97 Dodge Ram the onboard computer will recognize that and reset the light??

Thanks....Jason

 

AZ guy is probably right. when the pcm is satisfied with the results of the next few cycles of the evap system, it'll erase the code and turn off the light. it'll sort of depend on how much driving you do. might take 1-2 days, might take longer. if the light goes out on its own, then you'll know its fixed.

if you wanted to reverse the whole process, you can reset the pcm by removing the negative battery cable and turning the headlights on for 30 seconds. if you do this - if the light does NOT come back on in a few day, then you know its fixed.

 

That P0441 code is a PITA. I have yet to figure out a cycle where my light comes on and goes off. I can tell you that my gas mileage hasn't been hurt the slightest with this CEL. I just find it to be a nuisance when the light comes on.

 

Thanks again dhvaughan......

It's probably obvious to most.... but what do you mean by the "next few cycles" of the evap system?

And your second suggestion..... What does turning on the headlights do with resetting the light? I thought all I had to do was disconnect the negative battery cable.. Thanks

 

Thanks Laramie..... it is a pain in the behind...... I've never seen any degradation in performance when the light comes on.... But the light does really get your attention and can spoil a perfectly good day... My dog and I had a great day trip yesterday... put about 250 miles on the truck ........ then when we were within about 5 miles of the house in the dark the light came on.... I felt someone was shining a flashlight in my face....

 

the pcm operates the evap vapor purge process every once in awhile. that's a cycle. i don't know if it does it at every startup, or every so often on time, or every so often on mileage. but when it does, it uses sucks the evaporated gasoline out of the charcoal cannister and into the intake where it can be burned. it somehow monitors the success of this process by measuring pressure or vacuum or something.

i noticed that when i had my p0441 going on, after resetting the pcm it took 2-3 days for the cel to come back on. so the pcm either had a long delay between purge cycles, or a tolerance for failure before it set the CEL.

http://www.autoshop101.com/forms/h62.pdf


by design, the pcm contains some capacitors that hold power to the pcm memory, so that you can change a battery and not lose stored codes or adaptive (big word) memory. if you leave the battery disconnected long enough (an hour?), those capacitors will drain on their own. if you turn on the headlights, or turn the ignition to start, then the increased short to ground will drain the capacitors within about 30 secs. this is referred to as resetting the pcm.

 

a long time ago i used to be a real smart ***. i was traveling with my boss and we were going down the road in a rental car, just shooting the breeze. computer control/monitoring was a new concept back then and all of sudden the "check engine" light came on. he asked - reckon what that means? and i said - damned if i know, i've never seen it before, but the car seems to be running ok, so lets keep on going. a little farther on when we got off the expressway, i said, lets pull over here and "check the engine". he said ok, but what the heck are we going to check? so we pulled over and popped the hood and i figured it would be on fire or something but it wasn't. it was about 0 degrees and snow on the ground and i said - Bill, the engine's still there, so lets just keep going. He said, sounds good to me I don't want to walk.