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Discussion Starter #1
Does anyone have a walk through for replacing the Thermostat? My 01 Corolla threw code P0128. I searched but couldn't find anything. Thanks.
 

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Hi,

Before you just go ahead and replace the thermostat you should do a google search on code P0128 to see what it's all about. It may not even be your thermostat. Maybe your temperature sending unit is dirty and giving a low reading for example.

How to replace it? You should get a Haynes manual to give you general guidelines and torque specs.

Basically you will;

Drain the cooling system down
Remove the alternator
remove the water inlet
remove the thermostat
replace the thermostat gasket
replace the thermostat - make sure the jiggle valve is on top
install the water inlet - don't overtighten- torque is very small - 8 ft-lb
Install the alternator - torque 12mm head/18 ft-lb, 14mm head/39 in-lb.
Add coolant
Check for leaks
 

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Discussion Starter #3
Thanks for the reply, I am planning on picking up the Haynes manual today after work. Is there any chance that the thermostat can be removed without removing the alternator? I saw a thread on here where somebody just removed the thermostat bolts and voila, it was out without having to do everything else the book recommended.

P0128 just says thermostat malfunction and I haven't found a lot of information about it. It does seem like the thermostat is stuck open because the car takes a long time to warm up. Any other advice would be greatly appreciated. Thanks again.
 

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If you search for P0128 in Google you get 22,600 hits. Lots of forums from other cars say that they have replaced the thermostat but the code comes back. Of course a lot of them also say that the code never came back. Just lookin' at all the options before assuming it's the thermostat. It is a good clue that it is the thermostat when you say the car takes a long time to warm up.

I quoted the brief instructions about removal from the Corolla repair manual - without actually looking under the hood. I'll do that tonight after I leave work. I agree that some operations described in the manuals (including Haynes) don't always have to be done in order to achieve the objective. It's certainly worth a look and if you can do it without removing the alternator - great!
 
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