PO128 code
Thread Starter
Instructor
Joined: Nov 2008
Posts: 242
Likes: 17
PO128 code
driving at highway speed when DIC showed reduced power and no rev match, when arriving at home the radiator fan would not turn off until battery was disconnected. a forum search suggests either coolant sensor failure, or thermostat failure. Anyone have similar symptoms? ‘17 Z06
Racer
Joined: Oct 2016
Posts: 355
Likes: 65
From: Florida
take the scan tool , pull up vehicle live data for CLT , compare to ambient at cold start , start vehicle and see if it changes . No change in temp could be related to the sensor or a stuck open thermostat. Check sensor voltage at the connector ( its a thermistor ) so you will have to understand operation for an accurate check but basically the thermistor is on the ground side of the ECU internal circuit and its a voltage drop via the resistor. When unplugged should read 4.98-5v . As it gets warmer that voltage should change. You would need a scope to see the analog signal . Or you can do what most " techs " do , pull out the parts cannon ====> sensor ,then thermostat, then wiring, then ecm then take it to someone that knows lol.
Thread Starter
Instructor
Joined: Nov 2008
Posts: 242
Likes: 17
Fixed?
Thanks everyone for the replies. Replaced thermostat and thermostat housing after Checking hose leading from thermostat housing to radiator with a infrared thermometer, the hose coming from the thermostat housing showed a temperature of about 155 which was lower than it should have been with the engine warm, so deduced the thermostat was not closing properly. after replacing thermostat the hose coming from the thermostat housing showed a temperature of about 185 and a temperature on the thermostat housing of about 190 which is about what it should be. The thermostat that was replaced was closed when removed so it may have been and intermittent occurrence that the thermostat didn’t close properly, nevertheless, the engine has a new thermostat. About a 15-20 minute job on the Z06, easily accessible. Time will tell
Race Director
Joined: Mar 2010
Posts: 16,007
Likes: 827
Same as you, we want your Corvette running at peak performance. We think obtaining an official diagnosis from one of our GM-certified dealerships would be the next best step towards a resolution. If you'd like support connecting with one, you can reach us via email at socialmedia@gm.com. Just be sure to include your forum username in the subject line.
