2003 Toyota Prius engine overheating?

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Old 08 Apr 2014, 01:39 pm   #1 (permalink)
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Default 2003 Toyota Prius engine overheating?

Hi, I literally just turned my car on and right when I turned it on the engine overheating dash light came on. I haven't driven it anywhere it's been sitting outside for the past two days. And it's even cold and rainy out. How is the car overheating?
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Old 08 Apr 2014, 01:54 pm   #2 (permalink)
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Get rid of the prius. You may think it's economical, but, car for car, production included, it's pretty bad. Plus, fixes like that may be more expensive than the car itself, given it's age. Part exchange it for a better deisel car, including production, they're probably better than a prius.

It may just be the radiator or the fact that it's a s*** car.
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Old 08 Apr 2014, 02:25 pm   #3 (permalink)
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From my answer to the same question in Maintenance and Repairs:

Obviously it isn't actually overheating, it is just saying that it is even when the engine is stone cold. It almost certainly has to be a defective Engine Coolant Temperature (ECT) sensor, which is mounted in the end of the cylinder head almost directly under the inverter coolant reservoir. There is a plastic support above it that can probably be removed for better access but unless you are a determined DIYer I recommend the dealer because of the difficult access. Me? I'd bite the bullet and tear into it myself. A good place to start would be disconnecting the sensor and seeing what indication you get when you start it, and then putting the plug back on to see what you get then. If they are the same indication I would get a bad feeling about the wiring. If it shows the blue thermometer with the sensor unplugged and overheat with the sensor plugged in the sensor must be bad. If it suddenly starts behaving when you reconnect it you know the connector was dirty. Now all you have to do is figure out how to get your hand in there. BTW, the inverter coolant reservoir has a direct connection to the inverter so you can't just move it out of the way. The inverter can be moved a couple inches but the cowl has to be removed first - a half hour of grunt work. Once that is done there are just four bolts holding the inverter down and you should be able to get a couple inches movement that way.

One more thing.... Your 2003 should be coming up on its second coolant change. Replacing the ECT requires draining the engine coolant so if the coolant change is due, now's the time. True confessions - I never flush my Prius cooling system. The coolant has no silicates, borates, amines, or other chemicals that precipitate out so I just drain and fill with fresh Toyota LLC.
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