Engine Code P0128

TOYOTA HIGHLANDER
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HIGHLANDER2002
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Hi, any help is appreciated.

2002 toyota highlander.Automatic. 3.0 L V6 4wd. 100,000km.
Check engine light came on and my mechanic done a scan and ran this code P0128.

Mechanic said I probably need a new thermostat.

I went to the dealer to pick one up ($30.00) and he said he has never heard of that trouble with the highlander.

Toyota said they should have a look at it...Expensive...$100 just to scan for a code.

Confused at this point! Should I replace the thermostat and hope that was the problem? or let The dealer have a look?
May 15, 2007 at 12:24 PM
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UNCLE FESTER
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Try this Link:

https://www.2carpros.com/articles/mitchell1eautorepair-car-repair-manuals
May 15, 2007 at 12:40 PM
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HIGHLANDER2002
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Thanks . I had a look at the chart. I am not really sure what it all means.

My car knowledge is minimal. What is ECM. How much is one and ? labour time.

When the light came on the car was running for about 5 minutes
when they scanned that was the only code that came up.

Thanks again. Newbie
May 15, 2007 at 1:02 PM
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RASMATAZ
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That code is pointing at the thermostat being below the operating temperature.

The ECM ( Electronic Control Module ) is the Computer.
May 15, 2007 at 4:54 PM
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HIGHLANDER2002
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So should I just replace the Thermostat? Thanks Mb
May 15, 2007 at 5:26 PM
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RASMATAZ
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[quote:c545f81b6d="highlander2002"]So should I just replace the Thermostat? Thanks Mb[/quote:c545f81b6d]

Its a cheap fix go ahead and do so for a start.
May 15, 2007 at 6:27 PM
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ZONER CHICK
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You said your mechanic did a scan. Is that all that he did? Coolant level can also cause this light.

Check the coolant level, if it's low you need to find the leak and fix it If leak is at thermostat or water pump, you may as well change them. 100,000 is quite a bit of mileage. Refill cooling system, clear the code and see if it comes back.

If it does, change the thermostat if not already done. Refill, Clear, See if code comes back.

If it does, don't jump right to the ECM. Check the ECT (Engine Coolant Temperature) Circuit first. Basically it's the ECT sensor and the wiring to the ECM. If not the ECT you'll be looking at a ECM.
May 17, 2007 at 11:23 PM