Pressurized Systemn Warning...

[blktoptrvl]

I just got my second warning since I have owned the vehicle.

Tightening the cap will not solve it, so I am going to try replacing the cap again. This will be the second cap I have put on the gas tank in 4 years.

How often are you changing your gas caps?
Does anyone know of anyone who sells just a seal, as opposed to the whole cap?

[JCL]

I've never replaced a fuel cap. I have had the light come on three or four times, and simply undoing and retightening the cap has worked every time. It usually takes a few days for the light to go out on its own, in my experience.

[blktoptrvl]

Last time I changed the cap, I don't remember how long it took the SES to go out, but I don't think it was days. It has now been about 4 days since the light came on. I will give it a couple of days in case tightening does help.

Thanks.

[motordavid]

Same here, as JCL: orig cap, ('01), and have had that light twice in 11 yrs. A open and reclose made the light shut off both times. Didn't take long, if I remember.
GL, mD

[JCL]

Last time it happened for me was on our X3. The SES light came on. I had just put fuel in, and it was raining, so I had rushed back to the dry. When I checked the cap, it didn't seem loose, but I reinstalled it anyway, and waited. Took a full 7 days to go out, and we drove it for four of those days. No problems since.

[TerminatorX5]

on my E39 i had the green thingy on the cap disintegrate - the CEL was on for several years and did not bother me - it bothered the emission inspection stations though... lol...
I bought the green thingy from a dealer, couple of bucks, dealer was surprised to see the part existed in his warehouse but that was the extent of fuel cap adventures between the E34, E39 and two E53s that I had...
what does the code read? what about the filler neck - is it intact?

[blktoptrvl]

Originally Posted by TerminatorX5

on my E39 i had the green thingy on the cap disintegrate - the CEL was on for several years and did not bother me - it bothered the emission inspection stations though... lol...
I bought the green thingy from a dealer, couple of bucks, dealer was surprised to see the part existed in his warehouse but that was the extent of fuel cap adventures between the E34, E39 and two E53s that I had...
what does the code read? what about the filler neck - is it intact?

I did not know that the "green thingie" could be changed separately. Thanks I will try to get the dealer to get me one.

[Qsilver7]

Before spending money (perhaps needlessly)...can you share what codes you retrieved when you hooked up a code reader/scanner to your OBD II diagnostic connector?

Perhaps the fuel filler cap is not the culprit.

[blktoptrvl]

Originally Posted by Qsilver7

Before spending money (perhaps needlessly)...can you share what codes you retrieved when you hooked up a code reader/scanner to your OBD II diagnostic connector?

Perhaps the fuel filler cap is not the culprit.

I had it read at an auto shop (I don't have my scanner with me) and I forget the code number but it was "Evaporative System Malfunction, Small Leak" or something similar.

[Qsilver7]

Without knowing the correct OBD II code for sure...it could possible be any of the things mentioned below:

OBD II Code P0442


Evaporative System Malfunction, Small Leak

• OBD II P0442

Fault Code Definition

• Evaporative System Malfunction, Small Leak

Symptoms

• Check Engine Light will illuminate
• In most cases, there are no adverse conditions noticed by the driver
• In some cases, there may be a noticeable fuel odor caused by the release of fuel vapors

Common Problems That Trigger the P0442 Code

• Defective or damaged fuel cap
• Distorted or damaged Fuel Tank Filler Neck
• Small tear or puncture in the Evaporative system hose(s) and/or Carbon Canister
• Defective Fuel Tank Sending Unit gasket or seal
• Small split in a seam of the Carbon Canister
• Defective Evaporative Vent Valve and/or Evaporative Purge Valve
• Defective or damaged Fuel Tank
• Defective Fuel Tank Pressure Sensor
• Defective Leak Detection Pump
• Slightly loose and/or worn clamps or hardened O-rings anywhere in the EVAP system

Common Misdiagnoses

• Fuel cap
• Evaporative Purge Valve
• Evaporative Vent Valve

The Basics

The evaporative control (EVAP) system captures any raw fuel evaporating from the fuel storage system (e.g. the fuel tank, filler neck, and fuel cap). Under precise operating conditions—dictated by engine temperature, speed, and load—the EVAP system stores and purges these captured fuel vapors back into the combustion process.

Want to Learn More?

The EVAP system is designed not only to capture, store, and purge any raw fuel vapors that leak from areas in the Fuel Storage system, but also to run a series of self-tests that confirm or deny the operational and vapor holding ability of the system. This is an important task because at least 20 percent of vehicle-produced air pollution originates from malfunctioning Vehicle Fuel Storage systems.
There are many ways to "leak test" the EVAP system, but most perform the leak test when the vehicle is sitting (like over night) or during the initial start-up after the vehicle has been sitting over night. The EVAP system's operational performance is also tracked by the Powertrain Computer by reading the change in the oxygen sensor voltages and short term fuel trim whenever the stored vapors are released or "purged" back into the combustion process. These values should indicate that fuel is being added to the system and that the overall mixture is getting richer. The purging process occurs when the vehicle is under acceleration, which is when most vehicles require additional fuel.