Check ECT1 (up by the thermostat housing) for leakage or coolant ingress to the connectorMy daughter recently purchased a 08 Civic from a local guy off Craig's List. Turned out to be a neighbor to a good friend of mine. My friend said he took really good care of it, garage kept, etc., which was reassuring.
The thermostat spring must have been weak, it would open early. Threw a code for low coolant temp.
I changed the oil and filter, thermostat, coolant temp sensor, coolant, PCV valve, and air filter. All OEM parts.
There was no lining on the rear shoes, so I took it to a local mom and pop shop to have the drums turned and new shoes installed. They flushed the fluid out for me too. Also, one TPMS was bad, so they replaced it. Four new tires. The others had good tread but were dry rotted bad. Delinte DH2 tires, extra load rated and Z speed rating.
Then I drain and filled the trans (2.5 Qt), drove it 8 miles on a hilly road with a lot of curves (lots of shifting); then drained the trans again and changed the filter. OEM also. 2.75 Qt to fill.
I want to change the spark plugs yet and flush the power steering fluid. Later this summer or fall it will probably need front brakes.
BTW, what is up with the OM recommendation for checking the fluid level? It says to get it up to temp, then turn it off, wait 60 seconds but not more than 90 seconds, and check the level. What is their reasoning for that?
If a new thermostat doesn't fix your P0128, check
Service Bulletin 09-092 for more guidance, you might need ECT2 in the radiator and a pigtail
Honda AT fluid check procedures have always been weird
https://charm.li/Honda/2008/Civic L...sion/Transaxle/Service and Repair/Procedures/