Recent Topics
Changing brake fluid, clutch also?
by Darwin1138
09/30/14 10:20 AM
Low impedance US made multimeter
by JHZR2
09/30/14 09:43 AM
OnStar - Worthwhile?
by Dave Sherman
09/30/14 09:12 AM
Honda Oil Life - how works?
by sasilverbullet
09/30/14 09:02 AM
thinking of selling my escalade ext
by barkingspider
09/30/14 08:01 AM
Now think about it...
by CourierDriver
09/30/14 07:19 AM
Should i add more coolant?
by bowlofturtle
09/30/14 07:03 AM
Speed Bleeders Honda Fit
by Falken
09/30/14 06:35 AM
TGMO too thin?
by BTLew81
09/30/14 06:27 AM
Castrol Edge 5W30 A3/B4
by Shannow
09/30/14 05:34 AM
Some interesting ford charts and commentary
by Shannow
09/30/14 04:59 AM
How long may I use brake fluid after opening it?
by Ayrton
09/30/14 03:46 AM
Newest Members
JoshsCummins, Bushman03, luceze, moog8008, Jay_K
51452 Registered Users
Who's Online
101 registered (808Soldier, 901Memphis, 01rangerxl, abycat, 147_Grain, 13 invisible), 1820 Guests and 176 Spiders online.
Key: Admin, Global Mod, Mod
Forum Stats
51452 Members
64 Forums
220016 Topics
3473948 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: 2570
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 -173k mi
1994 Ford Explorer Sport -190k 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: 23981
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