P1116 / Overheating? Help fixing please

I would not replace parts based on a code that was pulled by an app that tells you what part to buy- hint, that app was designed to sell parts.
It might end up needing a new temp sensor but I would do some testing to confirm this. The problem I see is you don't have a location to safely work on your car. Plus, the sensor is located at the bottom of the heat storage tank , which can keep a couple quarts of coolant at scalding hot temps for 3 days.

Some thoughts about this: I would want to use a second app or scantool to make sure the code is accurate- sometimes I have have a scantool "lie" and give me incorrect codes or data. You would likely need a scantool/app that has Toyota specific coverage to read data for the heat tank temp sensor from the engine computer (most tools only have access to the limited "generic OBD2" data). On a fully warm engine I would expect all coolant sensors to read 180-210*F.

Temperature sensors are 2 wire Negative Temperature Coefficient devices (NTC). They vary resistance inversely with temp- while pulling a 5volt reference circuit toward ground (0V). So at when very cold, resistance is high and Voltage is near 5V. as it heats up, resistance goes down and voltage decreases steadily towards 0V.

If the code is correct, then something in the heat tank temp sensor circuit is not what the computer expects. If it is a high temp reading, then the voltage is low. How low? Could be a bad sensor, could be a short due to wiring damage or corrosion in a connector.

replacing the sensor MIGHT fix it, but that would be a guess.

Short form, I would recommend you take your car to a shop and have them diagnose this.

 

Most OBD2 readers have problems with accuracy for Prius... Dr. Prius app is designed specifically for Prius codes and subcodes and is essential to know what's wrong whenever a problem comes up. If you can get a refund on your existing code reader and buy one that's best for Dr. Prius you'll be better off in the long run: Hybrid battery diagnostic and repair tool for Toyota and Lexus

 

I've had a P1116 and replacing the sensor was an easy fix. However, it never overheated. It drove just fine, in fact. Are you sure you have enough coolant in the system? The over temperature alarm on your display combined with the sensor code, would send me right to the radiator.

 

Question for you. I recently began using Dr Prius- what systems does the app cover? I know it can pull engine control module codes as well as battery ecu. ABS? anything else? Does it only get data for the battery ecu?

 

It's not going to help you bleed your breaks or pull everything from every sensor, you need Toyota Techstream for that... But my understanding is it's going to pull the hybrid system subcodes and possibly other system subcodes, which most OBD2 readers can't pull... The app builder's philosophy is to create an app that will help you diagnose the most problems, while not directly competing with Toyota Techstream.