"Check Engine Soon" Code 128 meaning
canesrulealways
12-27-2005, 11:47 PM
2001 GMC Jimmy has intermittent "Check Engine Soon" light on. Diagnostic code 128 is what was enter when read. What does this code mean?
rlith
12-28-2005, 07:14 AM
2001 GMC Jimmy has intermittent "Check Engine Soon" light on. Diagnostic code 128 is what was enter when read. What does this code mean?
P0128 - Coolant Thermostat Below Thermostat Regulating Temperature
Did you try to swap to a cooler thermostat? If so don't go below a 180.
If you haven't swapped in a newer thermostat, your current one has probably gone bad and is stuck open.
If the latter is the case, considering it's a 2001, I would be nervous about DEX-COOL sludge in the cooling system.
Replace the thermostat and do an acid based flush on your system. I bet one of your symptoms as well is your heat isn't as hot as it used to be.
P0128 - Coolant Thermostat Below Thermostat Regulating Temperature
Did you try to swap to a cooler thermostat? If so don't go below a 180.
If you haven't swapped in a newer thermostat, your current one has probably gone bad and is stuck open.
If the latter is the case, considering it's a 2001, I would be nervous about DEX-COOL sludge in the cooling system.
Replace the thermostat and do an acid based flush on your system. I bet one of your symptoms as well is your heat isn't as hot as it used to be.
canesrulealways
12-29-2005, 07:58 PM
Thanks "rlith".
I had already flushed the system with little luck. Changed the thermostat this morning with a 195 degree one and so far no light and the heat's back to normal. Thanks again for the info.
I had already flushed the system with little luck. Changed the thermostat this morning with a 195 degree one and so far no light and the heat's back to normal. Thanks again for the info.
rlith
12-31-2005, 07:27 AM
Glad to hear everything is alright...:)
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