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Discussion Starter · #1 · (Edited)
Does my coolant temp seem kind of low? I had been driving for about 20 minutes.


I took my car to the dealer and they said that if there was an issue I’d get a check engine light. They said it checked out. I left the dealership and drove 5 miles and the temp barely hovered above 160, I turned around and brought it back to the service drive. I left it running and grabbed the service writer and showed him. He called the tech and after about 10 minutes he showed up with his laptop. By this time the temp with the car sitting warmed up to 180. He plugged his laptop and said the temp is where it should be. I told him on the freeway at 80 miles an hour it was sitting at 160. But it’s at 188 now, It’s fine. As soon as I got back on the freeway it dropped back down to 160. What could this be?


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Looks like a stuck open thermostat to me.


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Agreed thermostat not cycling back closed. My 2016 is closer to 200 normally at idle hot and at cruise. Not sure what the paramaters would be to trip a low coolant code and illuminate check engine light. ECU might need to see a certian temp after a specific amount of run time after a cold start to trip the code. Could be a pendoing code that has not tripped check engine light yet. Has anyone scanned? Tech can drive with scan tool and watch coolant temp in datastream to see if the coolent temp really is low or if the gauge is not reporting correctly.
 

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Discussion Starter · #4 ·
Looks like a stuck open thermostat to me.


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I told the dealer that it looks like a stuck open thermostat or a bad coolant temp sensor. But because I had no check engine light he said that those items were fine. The tech even had an attitude when I questioned him. He even asked me who said that the coolant temp shouldn’t be at 160? Really? I guess I need to find another dealer to go to.


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I told the dealer that it looks like a stuck open thermostat or a bad coolant temp sensor. But because I had no check engine light he said that those items were fine. The tech even had an attitude when I questioned him. He even asked me who said that the coolant temp shouldn’t be at 160? Really? I guess I need to find another dealer to go to.


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Yes find another dealer or change it yourself. It’s not that hard and it’s cheap. Not sure how hands on you are.


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Discussion Starter · #6 ·
Yes find another dealer or change it yourself. It’s not that hard and it’s cheap. Not sure how hands on you are.


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I’ve never worked on a supercharged engine, how difficult is it to burp the air pockets out?


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I’ve never worked on a supercharged engine, how difficult is it to burp the air pockets out?


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Supercharger cooling system is separate from the engine cooling system so really purging the air out on a an N/A or supercharged engine will be the same. There are tools to properly purge the air out of the system but you aren’t doing a huge repair and the thermostat is pretty high up. I don’t think it will be too hard to just replace it, top off the coolant level in the reservoir and let it run for a bit. Then after it cools, check the level again.


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OP, I had this issue right after getting the car with 4,650 miles on it. Turned out the T-stat wasn't working properly. It would show it running at operating temp (around 190°), then drop to 150°. I would get a dialogue box on the cluster that said "Reduced Power Mode".

The Code it tossed was P0128 - Coolant Thermostat: Coolant Temp below thermostat temperature.

A simple T-stat change, and I have had zero issues to date.
 
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