My dash temp gauge is acting lazy. Typically registering 210 but then it slowly floats down to 140, then back to 210. This laziness seems to happen at random times. Cooling system is working well otherwise.

What needs replacing to correct this problem? I know the earlier XJs had two coolant temperature sending units. I believe the '98 only has one (connected to thermostat housing)? 1998 4.0

 

It's most likely the temp sending unit. It's located in the Tstat housing.

 

I agree that it's the temp sending unit. But I know a lot of XJ's have 2 sending units. I would like to confirm that the 1998's only have one temp sending unit (t-stat housing) and it controls the dash gauge.

What year did they switch from 2 temp sending units to 1?

 

'97 -'01 use a single dual function switch which controls guage reading and electric fan engagement. It's in the Tstat housing.

 

Awesome, thanks for the help. Are there any replacement brands I should avoid, or are they all the same? I usually go to Napa or O'Reillys.

 

I got one at oreilly and it works great

 

What was the price on it? I'm seeing anywhere from $15-$60...

 

was either 16 or 26$....duralast maybe? cant remember

 

only got one on my 4 banger