Not a V8 but the wife has a 2019 Buick Lacrosse Essence 3.6l and the fan stays on after you turn off the car for a while. No engine codes but I noticed the temperature gauge stays all the way on cold.. thinking it's the coolant temp sensor. A quick Google search shows the temp sensor super hard to get to... anyone ever have this issue on a newer Buick or change the temp sensor?
A quick scan should reveal what the computer is seeing from the sensor.......why replace a part guessing
Yes, however, whenever it happens the temp gauge stays all the way cool. It's intermittent... sometime I start the car, the gauge doesn't work and the fan stays on... when the gauge works the fan acts normal.
May have a p0128 code. Verify coolant level is good. If so Most likely thermostat is intermittently sticking full open. Very common on the newer 3.6s
I think you might be right. I did throw that cold the first time it happened.. disconnected the battery and code went away... now it still happens randomly but no code ever comes back on.. I have a new coolant temp sensor but looks like you have to take the entire top of the engine off to get to it. Thermostat is right next to it so will probably replace that as well... I hate working on new cars..
Think of the sensor also working like a choke.....it not only tells the temp but when cold the computer knows it needs to enrich the fuel. All the same things happen with efi as do carbs....just differently. So if it reads full cold and never gets off it,......normally thsts around a -40 reading.....you will get full enrichment, just like a choke sticking on
Then the PCM would have to stay in Open Loop. Once the O2 sensors were looped in, the PCM would pull fuel and you would have large negative fuel trim numbers.
And the smell from the tailpipe would be horrible . And if you looked at the CAT it would probably be GLOWING
Car runs the same, no smell and same gas mileage. Weird. It looks like you have to take the entire top of the motor off to get to the thermostat and coolant temp sensor (might as well change them both). I called the dealer and they said $850 to change both.. Holy cow! I can't find any good videos on the procedure.. where are the Chilton's manuals these days haha. Anyone have access to service manuals on line? Or better at finding videos on a 2019 Buick Lacross Essence 3.6l? Thanks
You should be able to read engine temperature with a scan tool . It would also tell you if you are in Closer Loop or not . Its possible there are 2 sensors . 1 CTS for the computer and 1 for the gauge . Do you get heat from the heater ?? . Hell you can feel the hoses to see if they are HOT or luke warm .
For some reason, the logic in some PCM's is such that if an engine is running too hot or too cold it will turn the coolant fans on too much as it can't discern between the 2. It's a fail safe. Out of range, turn the fans on. So since the gauge is reading too low, how's is the heat? Yes, thermostats are common failures on this engine and they don't always set a P0128. The replacement thermostat comes attached to a long pipe which runs in the intake valley to the top of the trans. To save people money, we will separate the pipe from the thermostat housing and reuse the pipe with the new 0-ring. This reduces labor time considerably by not having to completely extract the pipe. Our GM dealer usually keeps about 7 of these thermostats in stock. I wouldn't even consider replacing the temp sensor. Nor would I even consider using an aftermarket thermostat.
Do double check the fluid level as that is one reason for the fail safe mode. If the fluid level is too low, the sensor is no longer submerged, so it can't read, but the engine is too hot due to lack of coolant.
Thanks. It's 25 degrees here. The fan and gauge worked correctly today. The radiator hose was warm but not hot after a 15 minute ride.
