P1821 Code (Again)

[James0816]

Well....it's getting colder out and with that, the dreaded P1821 code has reappeared. We chased this all last winter. Thermostat was replaced three times. Sensor twice. Once the warmer weather rolled around, no code. The temp gauge read right around 210 all spring/summer into fall. Temps have dropped into the low 40s/upper 30s at night. Now gauge reads just a bit over the middle hash mark between 150 and 210. <sigh>

There has to be something other than the thermostat or sensor going on here. but what? no clue here.

This is on our 04 TJ 2.4 manual btw.

Thanks as always.

 

[RMETeeJay]

P1281, correct?

I am not familiar with that engine, but does it have the electric fan? If so, is it possible that it's running when it shouldn't (during warmup)?

 

[James0816]

After reading RME's response, could this be a bad clutch fan maybe?

 

[RMETeeJay]

I also have a 2004, so I looked in my FSM. You have an electric fan. When you start it cold, does the fan run?