Check engine light was on....now it's off!

[Debra Co]

Well, this would be my second go around with the dreaded CEL. Last week it
went on steady. Stayed on for 4 days. I drove around ignoring it. Pretty
sure it wasn't the gas cap issue. Yesterday morning, it was no longer on.
About a year ago, it was on, took it to dealer, they reset the codes, I never
even found out what the codes meant.

Since it's off now, am I ok to just pretend this whole incident never happened?
I'm just out of warranty and don't really feel like paying for a diagnostic
visit.

The car is a 2002 OBW LL Bean 6 cyl, 40250 miles. In the past month alone, I
drove it hard at around 75-80 mph for 3000 miles. Could this have something to
do with it? Just about due for another oil change now, but didn't get one yet.

thanks!

 

[Alan Smith]

Has happened to me at least 4 times since the car was new (2001 VDC). First
two times I took it back to dealer and,both times, he allegedly replaced
something I think he called a "sender"in the gas tank. Both times, though,
he said no harm in driving car until he could take care of the fix ... a
week or two. Last two times I said "nuts" and just continued driving,
Problem eventually went away. Once, time before last, VDC Off light came on
at about same time as Engine Light. Within a day that returned to normal
and within a couple of days (fairly light local driving) engine light went
off too.

Frankly, I'm not sure just what the Check Engine Light is allegedly
checking, but, from my experience at least, it seems eminently disregardable
AS LONG AS THE CAR SEEMS TO BE RUNNING PROPERLY. If something else is
happening at the same time (back firing, stalling, excessive exhaust, power
loss, whatever) get thee to a dealer without hesitation.

 

[Alan]

In all cars, when the CEL light is on steady, it means that there is some
sort of problem with the emissions. It is nothing serious, and you can
continue driving the car. Many times, the condition clears up, and you are
left with a mystery. Could be water or in the gas, blocked air intake,
almost anything that would affect the emissions.If the light does not go out
by the next service, have them take a look.

If the CEL is fLaShInG, that is usually serious, and you should take the car
to the dealer immediately.

 

[Mickey]

Well, this would be my second go around with the dreaded CEL. Last week it
went on steady. Stayed on for 4 days. I drove around ignoring it. Pretty
sure it wasn't the gas cap issue. Yesterday morning, it was no longer on.
About a year ago, it was on, took it to dealer, they reset the codes, I never
even found out what the codes meant.

Since it's off now, am I ok to just pretend this whole incident never happened?
I'm just out of warranty and don't really feel like paying for a diagnostic
visit.

The car is a 2002 OBW LL Bean 6 cyl, 40250 miles. In the past month alone, I
drove it hard at around 75-80 mph for 3000 miles. Could this have something to
do with it? Just about due for another oil change now, but didn't get one yet.

thanks!

I wouldn't write off the gas cap just yet. Several months back I
had a problem with CEL coming on the going off numerous times for
almost a month. Finally took the cap off, cleaned off the filler neck
real good to insure it was real smooth, next removed the rubber seal
on the cap and cleaned it well. CEL hasn't been on since that time.

Mickey

 

[Sam Li]

Well, I would first find some place that would read the code for free, like
autozone, or 76 gas stations since there's no autozone near me, to read the
error code. If your CEL is on, there can be an error code stored in your
Engine Control Unit computer, and reading it can let you know what the ECU
"think" the problem is. If the light goes off then there's no code stored.

And yes a computer can always be fooled. There was once my CEL was on and
the error code told me there was leak in a pipe, I found no leak and reset
it. It never bothered me again.

Sam

 

[name]

Since it's off now, am I ok to just pretend this whole incident never happened?
I'm just out of warranty and don't really feel like paying for a diagnostic
visit.

The car is a 2002 OBW LL Bean 6 cyl, 40250 miles. In the past month alone, I

What makes this out of warranty?

 

[Skweezieweezie]

3Yr/36K all inclusive.

Engine and Powertrain mechanical
5Yr/60K miles, you pay for computer diagnostics.

 

[anon]

Just read this thread - my apologies if I am not replying in the correct
manner....

But can somebody please explain the fuel cap / CEL relationship for me?
I've never heard of this before. Is there sensors/wires in the filler
neck that register emissions???

Thanx in Advance
spinifex

 

[anon]

Just read this thread - my apologies if I am not replying in the correct
manner....

But can somebody please explain the fuel cap / CEL relationship for me?
I've never heard of this before. Is there sensors/wires in the filler
neck that register emissions???

Thanx in Advance
spinifex

 

[CompUser]

Just read this thread - my apologies if I am not replying in the correct
manner....

But can somebody please explain the fuel cap / CEL relationship for me?
I've never heard of this before. Is there sensors/wires in the filler
neck that register emissions???

It's not exclusive to Subies anymore...in the
quest to reduce emissions, raw fumes from
evaporating gasoline are also considered
pollution. I haven't done the "complete"
analysis, but I'd guess there's an "air" line to
the intake from the fuel tanks, that will put a
slight vacuum in the tank headspace, to pull
fumes into engine. There's a charcoal canister
back there too, that absorbs fumes during periods
of nonoperation, and should be in the draw-down
loop, too.

All that puts a slight vacuum on the tank
headspace, which includes the filler neck. If
the gas cap is loose, the vacuum won't develop.
A vac sensor in that area will notify ecu if the
proper vacuum level is not achieved, and the ecu
will store the corresponding error code, and
flash that darn lil light.

Steve

 

[Todd H.]

Just read this thread - my apologies if I am not replying in the
correct manner....

But can somebody please explain the fuel cap / CEL relationship for
me? I've never heard of this before. Is there sensors/wires in the
filler neck that register emissions???

There's an evaporative pressure sensor in modern fuel tanks to measure
the vapor pressure in the tank above the fuel.

Too low a pressure, and your CEL will come on indicating either a gas
cap seal failure, a hole in the tank, etc.

 

[John O]

Too low a pressure, and your CEL will come on indicating either a gas

cap seal failure, a hole in the tank, etc.

I wonder what the cost trade-off is for manufacturers to add a light that
says "Check fuel system" instead of the CEL??? Or even a special flash
sequence, or at least something more useful than the "something is wrong
with this huge piece of equipment, but it's top secret and it'll cost you to
learn what it is" light.

-John O

 

[Todd H.]

I wonder what the cost trade-off is for manufacturers to add a light that
says "Check fuel system" instead of the CEL??? Or even a special flash
sequence, or at least something more useful than the "something is wrong
with this huge piece of equipment, but it's top secret and it'll cost you to
learn what it is" light.

I'm told AutoZone will tell ya for free with their ODBII reader.

 

[Mickey]

I'm told AutoZone will tell ya for free with their ODBII reader.

Many of the codes are common regardless of mfgr. See the same
description for code number on my Ford CV. This is very confusing
when some codes mention bank 1 or bank 2. The bank info applies to
engines with separate systems for left and right banks you might find
in V6 and V8 engines.

On my car when the light came on the code was 420 which is a code for
the cat system, bank 1.

For all the hundreds of codes, some are not very useful in
understanding what is actually wrong.

Mickey

 

[Debra Co]

Thanks all for the good replies. The light remains off, and I'm still driving
around, so keep your fingers crossed!