Recent Topics
Cruise Ctrl on Rushmore Road Kings
by LoneRanger
10/31/14 02:56 PM
Happy Halloween BITOGers
by wavinwayne
10/31/14 02:44 PM
Durango 4.7 a dog in cold weather
by FLORIDA
10/31/14 02:02 PM
New AC Delco PF48E & PF48 Cut
by DirtyMoe21
10/31/14 01:50 PM
Shocks for a 1992 XJ?
by Finn
10/31/14 01:46 PM
01 taurus wont starter after new battery
by volk06
10/31/14 01:40 PM
Grese for dissimilar metals, rust/water/long time
by Henrik
10/31/14 01:28 PM
Royal Purple 75/w140 Synthetic:
by Doktor_Bert
10/31/14 12:33 PM
Diy LED Flood lights
by stockrex
10/31/14 12:12 PM
garden led lights and battery
by stockrex
10/31/14 12:11 PM
Under Valve Cover gm 5.7 201k miles
by Bryankkkk
10/31/14 11:36 AM
what tire to run for winter 4wd Tahoe ?
by Arctic388
10/31/14 10:29 AM
Newest Members
Thourun, Zach72, SandCastle, ymc226, redwoods73
51758 Registered Users
Who's Online
79 registered (95MarkVIII, 440Magnum, 943kgt, aquariuscsm, AandPDan, 94astro, 3 invisible), 1624 Guests and 172 Spiders online.
Key: Admin, Global Mod, Mod
Forum Stats
51758 Members
64 Forums
221465 Topics
3502295 Posts

Max Online: 2862 @ 07/07/14 03:10 PM
Donate to BITOG

Topic Options
#1253873 - 10/09/08 04:34 PM Code PO128- Thermostat??
exranger06 Online   confused


Registered: 01/25/08
Posts: 2616
Loc: Guilford, CT
My sister has a 2001 Saturn L200. The check engine light recently started coming on, so she takes it to Autozone and has them scan for codes. They came up with code PO128, "Engine coolant temp below thermostat temp."

I'm probably gonna replace the thermostat regardless, as I feel it's be a good maintenance thing to do. The only other thing I could possibly think of is maybe the coolant temp sensor. She said the fans were turning on even when it was really cold outside, which I think is probably normal, but it's also possible.

Anyone do a thermostat on one of these before? I know thermostats are generally very easy but I've never done one before, on any car. Any advice/insights/suggestions are very much appreciated.


Also, the thermostat located right where the upper radiator hose connects to the engine right? I know on most cars it is but this Saturn has some strange design elements from what I've seen so far.


Edited by exranger06 (10/09/08 04:43 PM)
_________________________
2006 Ford Ranger Sport -55k mi
1992 Honda Accord EX -174k mi
1994 Ford Explorer Sport -192k mi
1994 Ford Bronco XLT (project)

Top
#1253892 - 10/09/08 05:05 PM Re: Code PO128- Thermostat?? [Re: exranger06]
03cvpi Offline


Registered: 03/04/07
Posts: 144
Loc: Minneapolis
Fairly easy. Mouted on the front of the engine towards the pass side of the car. Don't loose the cardboard tube. The thermostat is pushed in and quarter turn to lock. If you have a mech mirror it's pretty easy to see. Most replacement t-stats come with the tube, if not a needle nose pliers will work, but on install be careful not to crush the t-stat.

Top
#1254329 - 10/10/08 09:46 AM Re: Code PO128- Thermostat?? [Re: 03cvpi]
eljefino Offline


Registered: 06/15/03
Posts: 24223
Loc: ME
^ That sounds right for a 1.9, is it the same for a 2.2 ecotec or 3 liter V6?

The fans will run when the car is cold if the AC is on, even as part of the defroster. If there's a CTS fault forcing the fans on there'll be a code for that too.

Diagnosing this much farther will probably take more time than the thermostat job. My experience with GM's is they usually fail cold, which is a good failsafe. \:\!

Top
#1254527 - 10/10/08 02:42 PM Re: Code PO128- Thermostat?? [Re: eljefino]
mechtech2 Offline


Registered: 09/05/06
Posts: 19479
Loc: Chicago Area
Make sure the mating surfaces are clean and corrosson free.
I am a fan of using a LIGHT coat of silicone RTV on gaskets and 'O' rings - no comebacks.
You may have a sensor problem. If the thermostat does not fix the problem, look there.

Top