I am getting these codes on my son's 2005 Pontiac Grandprix. P0128 P0300.... One is showing Thermostat but he said he replaced that last year... Any clue?
P0300 is a generic misfire code, P0128 can be many things, including the thermostat and coolant temp sensor. Look at this link.....http://www.obd-codes.com/p0128
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