I have seen this before. I'll bet you end up getting a new coolant temp sensor, or cylinder head temp sensor- whatever you want to call it. It's right between #2 and #3 spark plug. When it goes bad, for some reason, if floors the temp signal. There was a New Zealander who was on here who literally spent all his savings taking the car back and forth to the dealer. Each time it ended up with the same problem. He took our advice, self diagnosed it using the electronic odometer trick, double checked his temps with a cooking thermometer taped to the side of the upper radiator hose, and ended up replacing the sensor.
You can check it out for yourself. The electronic odometer trick should still work on a '11, but there might be multiple readouts- one for C and one for F. Earlier cars only have C. Here's what to do: Key off, press and hold the trip odometer reset button, turn key on, continue to hold until the odometer reads [test]. Release, and now each time you press and release the reset button, you will scroll through one of 30 test functions. Look for the one that reads [ 15 C] or whatever you think the temp of the engine should be at that time. You will remain in test mode until you turn the key off, so you can start the engine and drive around with this temp readout. From what I remember, his gauge would suddenly jump to 200 C, which is a ridiculous temperature for automotive engine coolant. Your hoses would melt in short order- and other nasty things happen. You can also double check this readout by using an infrared thermometer or cooking thermometer taped to the upper radiator hose. Use some good duct tape, and it will last for long enough for you to figure out what is going on. It won't last forever, of course. I'd go with the infrared thermometer, but I have lots of uses for those. Of course you can rely on good sense that a vehicle can't be running at 200C, so something must be messed up.
What I don't know is whether or not this car has the supplemental temp sensor on the thermostat housing. Some do, and some don't. Apparently yours doesn't, or the computer might at least be able (if it had code written for it) to double check the information it was getting.
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Originally Posted by the user formerly known as ZX3_Chick
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