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- - Code PO128 (https://67-72chevytrucks.com/vboard/showthread.php?t=517512)

ratrod67

04-01-2012 09:11 PM

Code PO128

Can anyone tell me what to replace to make this code stop? 2001 Silverado 4.8

PO128: Coolant temp below Thermostat regulating temp

edhtrd71

04-02-2012 02:37 AM

Re: Code PO128

Replace the thermostat. This dtc sets if a predetermined amount of time has gone by and the coolant temp is lower than the thermostats rating. The tstat is sticking open or opening to early. Very common on newer cars.

ratrod67

04-02-2012 06:15 AM

Re: Code PO128

Quote:

Originally Posted by edhtrd71 (Post 5289264)

Thanks for your reply. Is there anything else it can be? I replaced the thermostat 2 weekends ago and the code still comes back. Maybe a new thermostat that's bad??

truckdude239

04-03-2012 07:41 PM

Re: Code PO128

Bad temp sensor if the t-stat been changed

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