P 0128?

[CruseadorPT]

Engine light turned on and did the trick to retrieve the code and got that one... Anyone know what it is?

[CruseadorPT]

Oh nvm... just saw there is a little guide... Coolant Thermostat. At least its something small

[CREWZIN]

From PT D0-It-Yourself.net...

P0128 Thermostat Rationality - A rationality error has been detected for the thermostat.

Possible causes include:

Coolant Level
Coolant Temperature
Intermittent Condition

On another search, someone reset his PCM (Take the negative battery cable for for 5 minutes) and the fault code never came back.

SO: reset the PCM, check your coolant level, check for possible trapped air and check for proper coolant/water mix. Lastly, replace the thermostat.

[CruseadorPT]

will do... thanks

[CruseadorPT]

what do you mean with checking for trapped air?

[CREWZIN]

See if you have an air release nipple around the thermostat area. Be careful, it will be hot. When pressed with a air guage type end, it should release coolant, not any air.

[CruseadorPT]

will go do that right now... I'll get back when i finish everything.

[CruseadorPT]

checked and everything seemed ok... restarted the PCM and the light didnt turn on. so all good hehe

[CREWZIN]

Doesn't mean it won't pop up again but good luck.

[slartyblarfast]

Typically this code is caused by a bad thermostat or low coolant level. Most often it's the thermostat. Use to replace the thermostats on the 3.5 v6 in the 300's about every day. Most likely the thermostat is stuck open and does not allow the engine to heat quick enough.