1999 Jetta check engine light question

saxman wrote:

I have a 1999 (new body style) Jetta I just had a quick question about
my check engine light. It was extremely cold here a few days ago, and
I don't think I let the car warm up enough before I took off. As such,
the car ran a little rough at first, and the check engine light came
on. I stopped, let the car idle for a bit, and since then (2 days ago)
the car has run perfectly fine - but the check engine light is still
on. I'm planning on taking it to get the codes read, but my question
is this: Does the check engine light remaining on mean there could
still be a problem? Or does the light remain on after an error code is
stored (at least until the code is cleared)?

The reason that I ask the question is that the check engine light
seemed to come on because of a specific event (starting when too
cold). Since it runs perfectly normally now - my first thought is to
get the code read / cleared, and see if the light comes back on. Does
this sound reasonable?
Pobably the oxygen sensor getting tired...no matter the outside temperature.

I have a 1999 (new body style) Jetta I just had a quick question about
my check engine light. It was extremely cold here a few days ago, and
I don't think I let the car warm up enough before I took off. As such,
the car ran a little rough at first, and the check engine light came
on. I stopped, let the car idle for a bit, and since then (2 days ago)
the car has run perfectly fine - but the check engine light is still
on. I'm planning on taking it to get the codes read, but my question
is this: Does the check engine light remaining on mean there could
still be a problem? Or does the light remain on after an error code is
stored (at least until the code is cleared)?

The reason that I ask the question is that the check engine light
seemed to come on because of a specific event (starting when too
cold). Since it runs perfectly normally now - my first thought is to
get the code read / cleared, and see if the light comes back on. Does
this sound reasonable?

or maybe 100 or so other reason that can turn a mile light on. That's why
you need to post the fault codes, and I bet it's not the O2 sensors. "the
car ran a little rough at first"... my money is you have a few misfire
faults and if that's the case the MIL will turn itself off in a few more
days.



"al" <acickx111 (AT) gmail (DOT) com> wrote

saxman wrote:

I have a 1999 (new body style) Jetta I just had a quick question about
my check engine light. It was extremely cold here a few days ago, and
I don't think I let the car warm up enough before I took off. As such,
the car ran a little rough at first, and the check engine light came
on. I stopped, let the car idle for a bit, and since then (2 days ago)
the car has run perfectly fine - but the check engine light is still
on. I'm planning on taking it to get the codes read, but my question
is this: Does the check engine light remaining on mean there could
still be a problem? Or does the light remain on after an error code is
stored (at least until the code is cleared)?

The reason that I ask the question is that the check engine light
seemed to come on because of a specific event (starting when too
cold). Since it runs perfectly normally now - my first thought is to
get the code read / cleared, and see if the light comes back on. Does
this sound reasonable?
Pobably the oxygen sensor getting tired...no matter the outside
temperature.

"saxman" <erlloyd (AT) gmail (DOT) com> wrote

I have a 1999 (new body style) Jetta I just had a quick question about
my check engine light. It was extremely cold here a few days ago, and
I don't think I let the car warm up enough before I took off. As such,
the car ran a little rough at first, and the check engine light came
on. I stopped, let the car idle for a bit, and since then (2 days ago)
the car has run perfectly fine - but the check engine light is still
on. I'm planning on taking it to get the codes read, but my question
is this: Does the check engine light remaining on mean there could
still be a problem? Or does the light remain on after an error code is
stored (at least until the code is cleared)?

The reason that I ask the question is that the check engine light
seemed to come on because of a specific event (starting when too
cold). Since it runs perfectly normally now - my first thought is to
get the code read / cleared, and see if the light comes back on. Does
this sound reasonable?

I'd wait a little longer and see if it clears. If it ran rough the system
probably just detected a misfire and when it's "happy" that the misfire is a
random thing and not a constant recurring item it might go out.

I have a 1999 (new body style) Jetta I just had a quick question about
my check engine light. It was extremely cold here a few days ago, and
I don't think I let the car warm up enough before I took off. As such,
the car ran a little rough at first, and the check engine light came
on. I stopped, let the car idle for a bit, and since then (2 days ago)
the car has run perfectly fine - but the check engine light is still
on. I'm planning on taking it to get the codes read, but my question
is this: Does the check engine light remaining on mean there could
still be a problem? Or does the light remain on after an error code is
stored (at least until the code is cleared)?

Sometimes I have observed this if the car sat unused for a long time. I
haven't been able to reliably reproduce it because it happens under those
conditions only, for instance after such a period of non-use, the car will
not idle smoothly or idles at a higher rpm than normal until the condition
clears.

The light generally has to do with an emissions failure/warning and will
clear itself if the car is started without that condition recurring a few
times (might last a few days).

If the problem is recurring however this definitely requires attention.

--
Jem Berkes
www.sysdesign.ca