I had what I thought were two issues going on simultaneously with my 2015 Yukon Denali.
First, I got a check engine light and my scanner showed a P0711 code, which had something to do with the transmission temperature. This check engine line would come and go for about a month or two, and I was planning on taking it in soon. IT would stay on for 3 days, turn off for 2. Or turn on for a week and then be off for a few days. No other symptoms were noticed in terms of transmission issues. And nothing seemed to cause it - sometimes tie would happen first thing in the morning, sometimes after a trip, sometimes after only bein on the highway.
Second, my engine coolant thermostat and sensor needed to be replaced since the needle was showing no movement and my engine fan would run even after car was turned off. Two weeks ago, I changed them out. Since then, my PO711 code has disappeared, and I cannot get it to come back. I’ve run diagnostics, and nothing comes up.
Are these systems linked in some way that the engine coolant system was somehow affecting the transmission cooling system such that it threw the P0711 code?
BTW, just out of curiosity I had asked an AI if it was possible, and it indicated that it was, but I don’t trust it. and I want some professional advice on this.
Here’s what Perplexity said:
Based on the information provided, it’s possible that replacing the engine coolant thermostat resolved the P0711 code in your 2015 GMC Yukon Denali. While the P0711 code specifically relates to the transmission fluid temperature sensor circuit, there can be indirect connections between engine cooling and transmission temperature that explain this outcome:
The engine coolant and transmission fluid cooling systems are interconnected in many vehicles. A properly functioning engine cooling system helps regulate transmission fluid temperatures.
If the engine coolant thermostat was stuck open, it could have been causing the engine to run cooler than normal. This may have affected the transmission fluid temperature readings, triggering the P0711 code.
The transmission fluid temperature sensor uses the engine coolant temperature as a reference point. An improperly functioning engine thermostat could lead to inaccurate temperature readings, potentially triggering transmission-related codes.
Replacing the engine thermostat likely restored proper engine operating temperatures, which in turn allowed the transmission fluid to reach and maintain its optimal temperature range.
The P0711 code can sometimes be set due to issues with the powertrain control module’s (PCM) interpretation of temperature signals. Restoring proper engine temperatures may have resolved any discrepancies the PCM was detecting.
While it’s somewhat unusual for an engine coolant thermostat to directly cause a transmission-related code, the interconnected nature of these systems means it’s not impossible. If the code remains resolved and you’re not experiencing any other symptoms, it appears that replacing the engine thermostat may have indeed fixed the issue
The transmission fluid cooler is located inside the radiator.
If the thermostat was stuck partially closed, this would raise the coolant temperature, which in turn would also raise the transmission fluid temperature, which would then cause the P0711 code.