03 Check Engine Light Question

[TouchdownTN]

I have a 03 H2 with 60,000 miles. Onstar told me that it was due to a emissions problem. They told me to drive it a highway speed and the light may go off. They told me it shouldn't damage the truck and if the light did not go off to of course stop by my Hummer dealer which is 60 miles away and not open on my days off. Last night the light would flash then go back solid again then flash then go back solid. I haven't noticed the light flashing today, my question is am I doing any damage to my truck or is it ok to take my truck to a local mechanic and get them to turn off the check engine light with their programmer? Thanks for the help!

[mdoyle]

If you have an auto parts store near by they might have a code reader to loan at no charge. There is an OBD-II port under the dash near the steering column, you plug a reader into that and it will output either a code you look up in a book or the device name depending on the reader.

When it's emissions related the 02 sensor is a common suspect. I've also noticed that extremely cold weather tends to throw off the emission control equipment on my H2 which coincidently is an 03 with about the same mileage as yours.

I suspect when it's uber cold the MAF isn't doing it's job and the mix ratio is a little off which causes the O2 sensor to error out but that's just a guess.

[pdsq99f4]

Please don't just throw parts at the car without getting the code read first. Like mdoyle said, some auto parts stores will scan it for you for free (autozone is one of them). Post the code up here (will be P****) and then you can go from there. If the light is flashing it means that it is a catylist damaging problem, so have it looked at very soon. I would fix the problem and not just clear the light.

Pete

[8MYROVER]

Everytime it has happend to me was because the gas cap was not on properly. Take it and have the code read. Then take off the gas cap, put it back on then turn it three full clicks after it stops. Clear the code with the reader and see if that does not solve the problem totally. (If you know anyone who has any sort of OBDII power programmer most all of them will read and clear codes, even if it is not for your model vehicle, I have even used the one from my Duramax to clear codes on the H2)

[Klaus]

Malfunction Indicator Lamp
(Check Engine Light)

Your vehicle is equipped
with a computer which
monitors operation of the
fuel, ignition and emission
control systems.
This system is called OBD II (On

-Board
Diagnostics-Second Generation) and is intended
to assure that emissions are at acceptable levels for
the life of the vehicle, helping to produce a cleaner
environment. The CHECK ENGINE light comes on to
indicate that there is a problem and service is required.
Malfunctions often will be indicated by the system
before any problem is apparent. This may prevent more
serious damage to your vehicle. This system is also
designed to assist your service technician in correctly
diagnosing any malfunction.

NOTICE:

If you keep driving your vehicle with this light
on, after a while, your emission controls may not
work as well, your fuel economy may not be as
good and your engine may not run as smoothly.
This could lead to costly repairs that may not be
covered by your warranty.

NOTICE:

Modifications made to the engine, transmission,
exhaust, intake or fuel system of your vehicle
or the replacement of the original tires with
other than those of the same Tire Performance
Criteria (TPC) can affect your vehicle?s emission
controls and may cause this light to come on.
Modifications to these systems could lead to
costly repairs not covered by your warranty.
This may also result in a failure to pass a

required Emission Inspection/Maintenance test.

This light should come on, as a check to show you it is
working, when the ignition is on and the engine is not
running. If the light doesn?t come on, have it repaired.
This light will also come on during a malfunction in one
of two ways:

Light Flashing -- A misfire condition has been
detected. A misfire increases vehicle emissions and
may damage the emission control system on your
vehicle. Dealer or qualified service center diagnosis
and service may be required.

Light On Steady -- An emission control system
malfunction has been detected on your vehicle.
Dealer or qualified service center diagnosis and
service may be required.

If the Light Is Flashing

The following may prevent more serious damage to
your vehicle:

Reducing vehicle speed.

Avoiding hard accelerations.

Avoiding steep uphill grades.

If you are towing a trailer, reduce the amount of
cargo being hauled as soon as it is possible.

If the light stops flashing and remains on steady,
see ?If the Light Is On Steady? following.

If the light continues to flash, when it is safe to do so,

stop the vehicle

. Find a safe place to park your vehicle.
Turn the key off, wait at least 10 seconds and restart the
engine. If the light remains on steady, see ?If the Light
Is On Steady? following. If the light is still flashing,
follow the previous steps, and drive the vehicle to your
dealer or qualified service center for service.

If the Light Is On Steady

You may be able to correct the emission system
malfunction by considering the following:

Did you recently put fuel into your vehicle?

If so, reinstall the fuel cap, making sure to fully install
the cap. See ?Filling Your Tank? in the Index.
The diagnostic system can determine if the fuel cap
has been left off or improperly installed. A loose or
missing fuel cap will allow fuel to evaporate into the
atmosphere. A few driving trips with the cap properly
installed should turn the light off.

Did you just drive through a deep puddle of water?

If so, your electrical system may be wet. The condition
will usually be corrected when the electrical system

dries out. A few driving trips should turn the light off.

Have you recently changed brands of fuel?

If so, be sure to fuel your vehicle with quality fuel.
See ?Fuel? in the Index. Poor fuel quality will
cause your engine not to run as efficiently as
designed. You may notice this as stalling after
start

-up, stalling when you put the vehicle into gear,
misfiring, hesitation on acceleration or stumbling on
acceleration. (These conditions may go away once the
engine is warmed up.) This will be detected by the
system and cause the light to turn on.

If you experience one or more of these conditions,
change the fuel brand you use. It will require at least
one full tank of the proper fuel to turn the light off.

If none of the above steps have made the light turn off,
have your dealer or qualified service center check the
vehicle. Your dealer has the proper test equipment and
diagnostic tools to fix any mechanical or electrical

problems that may have developed.

[HUMTECH]

You can buy very inexpensive code readers these days, just bought one from MAC tools for 73.00 can and comes with A book with all the codes and descriptions. Is about the size of A key fob. very handy.

[phenom01515]

do you have a link to buy that?^^^

[mdoyle]

I bought a code reader a couple of years back. We were stranded in a small town with my Wife's Chrysler Town & Country, the transmission was in limp mode so we bought a code reader to reset it every so often to make it home.

Turned out to be a bad speed sensor and was fixed no charge out of warranty thanks to Keystone Chrysler.

Since then the code reader has come in handy several times for me, my neighbors, and co-workers. It's certainly paid for itself in diagnostic fees and probably paid for itself in free beers and meals via sharing.

I would not hesitate to buy one, they work on just about every vehicle made in the last 10 years. Shop around, some read codes out on screen in full text, others display a numerical code you have to look up in a book.

[TouchdownTN]

Thanks for all the help. I had a local mechanic read the codes and it is a catalytic converter problem and engine misfire. The Hummer dealer says that it should be under warranty (8yr/80k). I hope so because I was told it could be from $400 to over $1000 to fix. Thanks for the help!!!

[hummer74]

let us know what it was after the dealer is done with it. thanks

[Planohummer]

pcm and convertors are 8/80 wty with $0 ded. If the dealer tries to quote you for diagnosis up front that's fine, but once the convertor(s) is/are found at fault, the charge should go away.
The misfiring may also be intake gaskets, find out exactly what codes are present from the dealer.

[Ed G.]

Had the same problem last week. Lost some performance and mpg went down.Then the light came on, so I called OnStar. They said it was a problem with the emission system.The dealer said it would a couple days before they could take a look at it. For the hell of it I disconnected the negative cable and let it sit for a few hours. The next time I drove it the light went off, performance and mpg went up. Haven't had any problems since.

[pdsq99f4]

The misfire is caused by excessive backpressure in the exhaust due to clogged catylitic converters. Usually you will find the air filter is very dirty and causing the vehicle to run rich. This will take out the converters over time. Touchdown, I would check my air filter to be on the safe side.

[BUMMER]

Just wanted to revive this thread. My 03 H2 has 73000 miles, is this true that GM will cover all bad catalytic converters up to 80,000?. Or does this only apply to certain states. My H2 is registered in New York

[Easy Ed]

Just looked and took a pic of the warrenty info in the glove box in my 2003 and you are correct on the 80,000. Pic not to great but you should be able to see it good enough to see the one in question.

Ed
Attachment 52564

Originally Posted by BUMMER

Just wanted to revive this thread. My 03 H2 has 73000 miles, is this true that GM will cover all bad catalytic converters up to 80,000?. Or does this only apply to certain states. My H2 is registered in New York

[BUMMER]

Thank you Easy, thats exactly what I wanted to see. I called up my local dealer and it is in fact covered. Thank goodness bc I was going to pay my mechanic to have it replaced for $$$