Low fuel check engine light?

[sweetadad]

Last year, everytime my gas level would drop close to "E", the check engine light would come on. my mechanic said there might not be enough pressure building up, and suggested I change the gas cap, and that worked!!

Last week, my CEL when on again, but this time when it was 1/2 a tank...I thought it was something else, but upon topping up the tank twice, i notice that the CEL clears it self on top up and returns when the gas tank is 1/2 full.

Any ideas what might be wrong? The car is a 2001 Nissan Maxima.

Thanks guys,

[Pete_Coach]

If you think it is the gas cap, then try cleaning the area. Clean the cap as well as the threads and sealing surface of the tank.
The check engine light can come on for a number of reasons (actually almost hundreds of reasons) and many of them fuel related. Anything from a lower or intermittent fuel pressure sensed to emissions systems signals.
I would get the codes read just to be certain you are not doing permanent and expensive damage.

[sweetadad]

Last time I did clean the mouth of the gas openeing with some sand paper and then put tremclad paint on it to thicken the opening up. I guess I can try it out again...thanks

[skidz88]

Get the code pulled. Drop by any Partsource and pay them $15 to pull the code for you. I can most likely help you if I know the code. My guess is it will be P0455 or something else evap related.

[Pete_Coach]

Last time I did clean the mouth of the gas openeing with some sand paper and then put tremclad paint on it to thicken the opening up. I guess I can try it out again...thanks
Actually, I was more thinking you clean it good and perhaps put some lubricant like Vaseline on lip and the ribber seal. If you sand it, make sure it is very very fine and painting is never a good idea. If paint flakes off, it does not dissolve in the gas, that is also why I suggest Vaseline instead of a silicone lubricant.
Have you ever changed the fuel filter?
The other thing you can do is clear all existing codes and start fresh. Disconnect the battery for 1/2 hour or so and reconnect. This clears stored codes and any new codes or lights will be singular rather a than cumulative sensor readings. You have to have your radio code, or it may not work. Not sure about Nissan.

[sweetadad]

Get the code pulled. Drop by any Partsource and pay them $15 to pull the code for you. I can most likely help you if I know the code. My guess is it will be P0455 or something else evap related.

Hi skidz,

Last year, I did get it checked and it was the P0445 code (evap can leak)...the local mechanic I had was asking $400 to fix it ( he said he had to replace the canister behind the rear wheel)....but also suggested that I try replacing the gas cap (which worked uptil now).

Any ideas on how hard it is to change it myself?

[Frankie3s]

Hi skidz,

Last year, I did get it checked and it was the P0445 code (evap can leak)...the local mechanic I had was asking $400 to fix it ( he said he had to replace the canister behind the rear wheel)....but also suggested that I try replacing the gas cap (which worked uptil now).

Any ideas on how hard it is to change it myself?

It might be cheaper to buy another gas cap and try it again. Maybe the other cap had deteriorated in some way? If not, you might be able to return the newly purchased gas cap for a refund.

[macnut]

I wouldn't rush to replace the evap. cannister - it is could be just a connecting hose leak that is triggering the CEL.

The timing of the light coming on and the level of fuel I don't think is connected - and replacing the cap last year with an apparent temporary resolution could be coincidental.

I would wait it out til better weather allows you to check around the back wheel arch for any accessible evap. hoses and clamps and tighten or replace as appropriate.

[skidz88]

Hi skidz,

Last year, I did get it checked and it was the P0445 code (evap can leak)...the local mechanic I had was asking $400 to fix it ( he said he had to replace the canister behind the rear wheel)....but also suggested that I try replacing the gas cap (which worked uptil now).

Any ideas on how hard it is to change it myself?


The evap assembly is known to fail on Maximas that are 5+ years old in my experience. It did on my 03 Maxima, and I know of 4 other friends who've had this happen to their Maximas.

It's not the canister itself, but the vent valve that goes bad and stays stuck open causing the code. Problem is the assembly is so old by now that the vent valve has bonded itself to the canister and trying to remove the valve almost always results in cracking the canister. Parts are about $300 from the dealer, and labour is only a 20 min deal. You can view the canister itself if you look under the car behind the left rear wheel. Honestly, I got a used canister and vent valve from a wreckers yard for $100 and it's held up for over a year now.

If you want, there's a simple way of seeing if the canister works or not. Get a friend to turn the key to ON position, without starting the car. Put your ear up to the canister and you should hear it click, if you don't then it's stuck. There's a certain spot you can give it a whack with a hammer, and the valve should shut but I doubt you'd know where that is. Just listen for the click and if you don't hear it call up a local wreckers yard and pick up a used canster/valve assembly.

Also, just because you got the car scanned last year and the code P0455 came up doesn't mean a new code isn't coming up along with it now. Accompanied by your P0455 might be a P1448.