Code: P0125

[Mike6158]

My MIL came on during a fast round trip from Texas to Florida and back on the 4th. I thought that it was because I was using unleaded fuel rather than premium so I put a tank of premium through the TLC then a tank of mid grade. Sometime after the second tank the light went off.

I checked the code and this is what shows up

P0125 Insufficient Coolant Temperature for Closed Loop

Apparently it wasn't the fuel

Speaking of fuel- do I have to run premium?

 

[CanadianRockyCruiser]

Likely your cause is one of the following:
-Low engine coolant level
-Leaking or stuck open thermostat
-Faulty coolant temperature sensor

You don't need to run premium. Some members have suggested better fuel economy with premium: If that is true, then it might be worthwhile.

 

[Mike6158]

I'm thinking sensor. Fluid levels are fine. The engine wasn't running cool. Also, at idle, just after start up, when the engine coolant is 100 degrees, it doesn't throw the code.

I just happened to do a mileage test on my one day trip to Florida and back. The speed I drove had more to do with economy than the fuel I used

R = regular
M = mid grade
P = premium

Odometer Mileage Gallons Fuel Grade MPG
153,025
153,147 122 8.112 R 15.039
153,307 160 10.876 R 14.711
153,524 217 13.459 R 16.123
153,831 307 18.925 P 16.222
154,030 199 11.768 M 16.910
154,212 182 11.818 M 15.400
154,482 270 16.503 M 16.361

 

[Mike6158]

I just did a 5000k plus road trip from Texas to Maine and back and I didn't have a single problem. Idk what the other deal was