Anyway to get rid of the 0128 code??

[beefcake]

I get this code every 2 weeks or so on the car,

any way to get rid of this??

i've got a 160 tstat

[GoofyTimL]

I believe that is the Tstat Rationality code. It comes from the coolant temperature NOT reaching at least 180 F within a specified amount of time or driving. A 160Tstat isn't recommended for daily driving, but is good for the track to help the engine cool rapidly after a run.

If you don't have a fan mod, then you shouldn't have any difficulty reaching 180 in city or stop/go driving. However, if you just crank her up and take off (45 mph or higher) in the morning and the ambient temp is 50 or less, you risk not getting the temp high enough fast enough due to airflow through the radiator (my experience).

Here's what I do during the winter... run in autostick and keep the revs up until 180F is reached (you can observe the coolant temperature through the diagnostic display of the EVIC - hold the menu and music buttons simultaneously for 7-10 sec and the diagnostic display will appear, then cycle through to engine temp). Under 46 mph I stay in 3rd. For 65 mph I stay in 4th until temp. is reached. Haven't thrown a code since I started driving this way during the colder months. Works just as well with the 300C by negating MDS operation until 180F has been reached.

A DiabloSport Predator tuner then can/could be used to clear the code. Otherwise, if memory serves you have to have three "good" driving cycles before the code will self-clear.

[stevesrt8]

good show there, tim.

All answers given correctly, just one thing to add.

That 160 is way too cold for any modern engine. You will not get enough warmth to satisfy the computer, and you may have other issues as well.

Two well proven thermostats are the 4127, which in my car runs 179, and the 4128 which will be 185 or so (your temp may vary a little). So we think the 4127 for the warmer areas and the 4128 for the northern guys.

Autosticking is essential to generate enough heat to avoid that code. It takes three times to set it and 3 times to remove it. It clears quickly and easily with a Predator.

[joey]

I believe pulling fuse 11 will clear the code.
Predator and Flashpaq can also clear the code.


From the Service Manual.

P0128-THERMOSTAT RATIONALITY
² When Monitored:
Engine running.
² Set Condition:
The PCM predicts a coolant temperature value that it will compare to the actual coolant temperature. A significant
difference results in an error. Two Trip Fault. Three good trips to turn off the MIL.


I have had a few P0128 codes and cleared them with my Flashpaq. One time I wanted to verify the Service Manual "Three good trips to turn off the MIL".

So I drove about a week with probably 10 or more "good trips" before the MIL disappeared. I was very careful during this period to ensure I didn't have a "bad trip". Based on my test, there seems to be a difference in how the car sets the threshold temps and/or operations when setting a "Two Trip Fault", compared to how it sets the thresholds to generate 3 good trips.

[AP24LA]

I have been getting this constantly now that its getting colder here. I clear it and have turned my fans back to stock but it still seems like I always run really cold and it pops back up within a day or so. I dont really mind it but just wanna make sure that running at about 180, which is what its normally at, wont have any negative effects on the car. Anything to be worried about?

[Rambit]

Originally Posted by AP24LA

I have been getting this constantly now that its getting colder here. I clear it and have turned my fans back to stock but it still seems like I always run really cold and it pops back up within a day or so. I dont really mind it but just wanna make sure that running at about 180, which is what its normally at, wont have any negative effects on the car. Anything to be worried about?

It's just that your engine has to reach a specified temp within a certain period of time. Now that it's colder you'll see this happening more unless you can bring it up to temp faster, as has been mentioned by less warm up time and driving in autostick. Happens this time every year for those with the lower temp t-stats.

Bernie

[AP24LA]

So nothing too serious. Thanks Bernie.

[DESIREE]

My 4128 popped a CEL the other day. I wasn't in any hurry on wet back roads with the ambient temperature at about 45*F.

It just served to remind me that I need to make up a partial cover for installation in front of the radiator, like I did last year. Then just remove it in the Spring when morning temperatures are more like 50*F+.

"It works for me!"

[Rambit]

Hey man, that's old school and I can remember doing that back in the day. Sounds like it should work too.

Bernie

[DESIREE]

Originally Posted by Rambit

Hey man, that's old school and I can remember doing that back in the day. Sounds like it should work too.

Bernie

It's "old school" alright because I am an old student!
Back in the late 50s/early 60s I remember Volvos having a window shade-type contraption that raised from the bottom of the radiator as you pulled the knob inside the passenger compartment.

For what it's worth, this year I whipped up a 23" long by 12" wide piece of trash bag duct taped to a steel rod along the 23" edge, and suspended it behind and below the power steering cooler and infront of the radiator from the bracing that spans between the radiator crossmember and the backside of the grill with a couple of strands of wire.

The completed assembly looks like this: