97 lesabre Check engine light on

I have a 97 lesabre limited. The check engine light came on every time I drove on the expressway(usually higher than 60 mph). The light turned off after some miles at local area. What kind of problem should this be? The car runs fine at 18 MPG. Any help is appreciated.

I have a 97 lesabre limited. The check engine light came on every time I drove on the expressway(usually higher than 60 mph). The light turned off after some miles at local area. What kind of problem should this be? The car runs fine at 18 MPG. Any help is appreciated.

Welcome on your first post on AF.
If the check engine light comes on you need to have codes read and post back codes.
Some auto parts places give free code checks BUT.
Use Caution when getting the free code checks please.
Some parts places do offer free code checks. And also free repair advice. But beware. Just get the code no and post it back here and someone will help you.
They offer the free code checks in the hope of increasing there parts sales.
Almost all of them will also offer mechanical advice and some know what they are doing.
But just remember most of them are parts people pulling codes for free.
Not trained professional tech/mechanics. Even if they pull a 02-sensor code or another sensor related code it does always mean to replace that sensor and your problem will be fixed.
Please just get the code no and post it back here and we will help you.

Also
Tips on getting a good answer to your questions.
People trying to answer your question do not have a crystal ball.
So give them all of the info you have like year make and model and engine and transmission and mileage.
Also service cars engine and transmission service history or any recent repairs or problems.
Also a description of your problem and what it is doing or not doing.
If you have codes give up the code no.
And remember a code does not say replace the part but only points to the problem that you have to check out.
So to better help you give up all of the info you have on it.
MT

Welcome on your first post on AF.
If the check engine light comes on you need to have codes read and post back codes.
Some auto parts places give free code checks BUT.
Use Caution when getting the free code checks please.
Some parts places do offer free code checks. And also free repair advice. But beware. Just get the code no and post it back here and someone will help you.
They offer the free code checks in the hope of increasing there parts sales.
Almost all of them will also offer mechanical advice and some know what they are doing.
But just remember most of them are parts people pulling codes for free.
Not trained professional tech/mechanics. Even if they pull a 02-sensor code or another sensor related code it does always mean to replace that sensor and your problem will be fixed.
Please just get the code no and post it back here and we will help you.

Also
Tips on getting a good answer to your questions.
People trying to answer your question do not have a crystal ball.
So give them all of the info you have like year make and model and engine and transmission and mileage.
Also service cars engine and transmission service history or any recent repairs or problems.
Also a description of your problem and what it is doing or not doing.
If you have codes give up the code no.
And remember a code does not say replace the part but only points to the problem that you have to check out.
So to better help you give up all of the info you have on it.
MT

Thanks a lot. I will do the code check soon.:wink:
BTW: the car is 1997 lesabre limited. 120000 Miles. The mechanic check showed no problem with the engine and transmission when I purchased this car 4 months ago.

I drove to autozone for the code today. It shows P303. The guy at autozone told me this means the 3rd cylinder misfired when I drove on highway.(I am not sure)
Is this a big problem? The check engine light came on 5 days before and turned off one day after that. Is this a correct code for the check engine light 5 days before?
Thanks a lot.

I drove to autozone for the code today. It shows P303. The guy at autozone told me this means the 3rd cylinder misfired when I drove on highway.(I am not sure)
Is this a big problem? The check engine light came on 5 days before and turned off one day after that. Is this a correct code for the check engine light 5 days before?
Thanks a lot.


If he read it as a code yes it is.
History or nocurrent codes are stored in the history section.
A missfire is a big problem.
It can damage your engine and run your cat.
A missfire usually causes a flashing check engine light.
When you get both a flashing light and a code your cat and engine is in danger.

You need to start with a good tune up and look for that missfire.
When was your last tune up?
MT

If he read it as a code yes it is.
History or nocurrent codes are stored in the history section.
A missfire is a big problem.
It can damage your engine and run your cat.
A missfire usually causes a flashing check engine light.
When you get both a flashing light and a code your cat and engine is in danger.

You need to start with a good tune up and look for that missfire.
When was your last tune up?
MT

The engine light came on steady not flash every time I drove on the highway. And the light turns off on local driving, does this mean that there is no such problem for local driving? I got this car one month ago. I do not know when the previous owner did the last maintenance? I only changed the oil last month. Maybe I need to do a mechanical check recently.

Your problem may or may not be an actual misfire, especially if you claim it runs fine other than the SES/CEL light coming on for that short duration of time. Other issues could cause your problem.

A scan with a odb-ii scan tool capable of reading GM extended codes may help. The DTC (diagnostic trouble code) history can be reviewed and a scanner can be left connected to the data link port to check live engine data parameters (PIDs) and freeze frame data. This may be the route to go since the SES/CEL extinguishes. Most auto mechanics have scan tools like a Snap On MT2500, etc. capable of doing this and of course, including the GM dealer who will use a Tech II.

Check the easy stuff first. Look for a loose or bad plug wire on cyl #3. Push it on and make sure it is good and snug. I have had this problem a few times before on my Lesabre. Sometimes the wires work loose. Might check to make sure the wires are snug on the coils too. If it warms up sometimes they don't miss as bad. I have found that if the wire is bad or loose, they will sometimes run worse in cold weather and improve as the day gets warmer. Might be time for a new set of plugs and wires as mentioned. Get AC Delco if you do. Might will improve you mileage some. Mine gets 23 combined highway/city. I drive a lot of highway in that though.