nate579

iTrader: (4)

In the winter for some reason my car run cool, basically the guage is a little over the first notch on the temp guage, instead of in the middle. I will let the car warm up but as soon as I hit the highway to work (40 miles 1 way all highway), the temp drops to the first notch. The other night I was in a rush and didn't have time to let the car warm up. But I did drive slowly until the guage read normal then as soon as I hit the highway it dropped below the first notch and CEL. Code Reader shows a 0128 I think, something like coolant temp to low for reading, not precise but that was the gist of what the reader was saying. Ambiant Temp was 13 degrees that night. Since then no problem but still low reading when I hit the highway. City driving due to stop and go traffic it will actually remain in the middle.

Questions:
1. Is there something I should be concerned about?
2. Has anyone else had this problem and what was your rememdy?
3. GS has 92k miles, I usually park in the winter, the car was sitting in the garage for 4 weeks before I drove to work that night. Do I need to drive it more often?

Thanks for your in advance as usual.
I think a major tuneup is due. Might need it sooner I guess.

Solo_D33A

https://www.clublexus.com/forums/gs-...cel-codes.html

I drive in -20-40 area with coolent temp no problem at all. drove on Trans-Canada highway with -22F outside, man the car's powerful. lol

FlavesLex

iTrader: (1)

If I had to take a wild guess off the top of my head, I would say you have a stuck thermostat in the open position, or no thermostat at all. This happened to me on an older car, and since it took so long to warm up in winter, I decided to finally install the thermostat.

Good Luck and keep us posted

FrankT

P0128 COOLANT THERMOSTAT (COOLANT TEMPERATURE BELOW THERMOSTAT REGULATING TEMPERATURE)

x2 on a stuck open thermostat.

If the engine coolant temperature becomes less than 75 °C (167 °F) , it is abnormal.

I would clear the code and if it pops up again, buy a new thermostat.

Solo_D33A

oh, it's 0128, thought it's 1128... lol (Self Owned)

Spyder78

iTrader: (7)

Thermostat Stuck open its a very easy fix takes about 20 minutes and new thermostat is like $20.

COOLIS

My thermostat just went while I was up in Mammoth, CA 2 weeks ago. It was around 35-40 the whole week except for at night. My car would overheat then drop down to normal temp. I was never able to get heat though, it always blew cold air. Thermostat was the problem.

KiPod

iTrader: (31)

Just as a heads up there are also 2 Water Temp Sensors as well. I would do thermostat first though.

gserep1

I think this is a thermostat as well. This is cold weather operation, so th ethermostat has to struggle to keep the coolant warm enough for the heater, and to put the engine in "closed loop" for emission control purposes. I live in California, so I never see the temperatures people see in other parts of the country.

I change my coolant fairly often since I put on so many miles. I make it a habit to c hange my thermostat everytime I change the timing belt, which is at 90,000 miles. I have 190,000 miles so far and the thermostat has been changed twice by me. My coolant stays clean and never had an overheating problem.

For those that pout on mileage at a much more normal rate, I would say check and replace coolant no later than once in 3 years regardless of miles. To me that is long life....not (7 or 8 years).

Change out that thermostat and coolant using distilled water, (or get the Lexus red pre-mixed coolant for best results. If the existing coolant looks scummy, I'd remove the thermostat and reinstall the cover and flush with distilled water only. get it up to operating temperature and let it run back out. Make sure you turn your heater on as well to get the distilled water into the heater core. I'm pretty ****-retentive on keeping the cooling system clean.

On my GS400 I even drain the block by removing the block plugs and let it all drain out.

Check your hoses. I finally changed mine after 190,000 miles. They looked good, but I felt 10 years was enough.