Code PO128 on 2005 Chevrolet Trailblazer

I replaced the coolant temp sensor. I am still getting a PO128 code. I tested the sensor and it tests good. The gauge reads 200. What else could be causing the code?

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1 answer 1 comment
Did you replace the thermostat as suggested before? You say temp. reads 200 but is it constant while driving down the road? Unless you have a REAL scanner a DVOM and the savvy to use them, get a mechanic to have a look. Circuit or ecm problem, will have to be tested.
I have same problem. Always get same code. Now have intermittent starting problems and no mechanic around can seem to find the problem.