Okay, this may have been covered numerous times, but a search didn't reveal the answers I'm looking for. I got in my '04 MC CVT this morning to go to work (outside temp about 10 degrees F). The car started and stalled (this I've grown used to). So I started it up again, to be welcomed by a very rough idle and a flashing SES light. So I shut it off and took a different car to work.

When I got home, I started the car again. Smooth idle, but the SES light remains illuminated, but at least not flashing. It had about a 1/2 tank of fuel, so I took it and filled it up. The light remains illuminated. Any thoughts from anyone?

The earliest I can get to my nearest dealer (100 miles away) is Wednesday. Is it safe to use the car until then?

 

I have an MCS, one cold morning the same thing happend. I was scared as I thought it could have been from my upgrades. Go to an autozone or pepboys and ask for the loaner OBD2 code checker/clearer.

I did this with mine and checked it the error code that signaled the SES light was P0128 - "Coolant Temp Below Thermostate" a fellow NAM member told me that it was because I gave it too much gas before the engine was heated up enough.

Since you were starting from a stalled, rough idling engine. This could also be ur problem.

 

Same thing happened to me Wen! I have not yet upgraded to v39, but one cold morning my SEL light came on and stayed on...car seemed to be running great. The Autozone OBD II Scanner read the same code as yours--re: the thermostat. I cleared the code, and it stayed off awhile.

In the owner's manual it says the SEL light is a caution light--its ok to drive the car, just plan on getting it looked at...its not a red malfunction light...

When I took my car in, I told them about the SEL light (which was now off...) they said they found a fault indicating faulty thermostat, so they replaced mine under warranty...though I had not had any overheating problems...

 

crank it 3-4 more times and it'll go off. The car auto resets after 5
startups if the problem went away.

After you clear the service engine light, in the future see if this helps:

Turn the key to the on position and wait 5 seconds. If you have DSC,
the DSC light will go off. Then twist the key all the way to the start
the engine.

If you have access to a local auto parts store like an Autozone, they
can read your OBDII code to tell you what triggered it. but imho if the
car starts fine and the light doesn't come on again, you're probably okay.

 

hmm, yeah, maybe i will go in and have them check it out. I have had the SEL come on twice now. both with the error code P0128 - the coolant one.

 

I'm getting that same error code. I've had it 3 times previously and just cleared it. This time I'm taking it to the dealer and having them fix it. My guess, from reading here and other boards, is that I'll get a new thermostat.

 

After upgrading to v39.x, I had the same error code and SES light stayed on, took it to the dealer, they replaced the defective thermostat. Maybe V39 is more sensitive to thermostat setting.

retroom

 

An update on the SES light:... a week after replacing the thermostat, the SES light came on again this Friday. The car runs fine, I'll drive it over the weekend and see if the light goes out.

retroom

 

I have gotten the P0128 SES code a number of times. For me, it happens well after the car is warmed up, after 10-15 minutes of driving.

I use one of the Davis Car Chip OBD loggers, and I have one parameter logging engine temp. At the times when the SES light comes on, the car is all warmed up, and the logged data shows nothing funny -- Temp running between 190 & 200F, steady as a rock.

Fortunately, The Davis OBD2 widget allows me to reset the SES light. And it always comes back with the P0128 "Low Coolant Temp" error. Its a 45 min drive to the local dealer. I'll continue to reset it, and not worry until some time when I plan to be in their neighborhood.

Can anyone report for certain that replacing the thermostat (presumably to raise the temperature a bit) actually fixes the seemingly bogus SES warning?

Tom

 

My SEL light for the thermostat/coolant "problem" went off BEFORE I was into the dealer, so I know v39 wasn't loaded...(but MTH was loaded a week before...which may have nothing to do with it).

Car ran fine, cleared the code myself with OBDII (it didn't go off by itself, despite driving for a week or so..)

Dealer did 30K service and they didn't mention it, but car had to come back for another problem and I remembered to mention it to them, so when they checked for problem codes (thought they would do that with the service!) they noted "the thermostat needed replacing"....got it done, and no light since (only about 750mi) they did note that my coolant protection was something like "-60" on the work notes for the maintenance...I had thought maybe it had something to do with the coolant being ineffective, since my light came on when it was pretty cold out! Guess not...