Hello
My 2007 Jag XK just showed a check engine code of P0128.
Any insight into what this is and how to fix?
I cleared the code and it came back within 40 miles.
Thank you for any assistance!
Charlie

 

Hey Charlie. I'm not sure why your first action to getting a trouble code is to clear it, but it's seldom the right approach. On to your potential problems.

P012800
Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)

Caused by
• Low/contaminated coolant
• Thermostat
• Cooling fan circuit(s)/module

Resolve by
• Drain and re- fill cooling system to correct level and specification. Check for and repair leaks.
• Check and install a new engine thermostat as necessary.
• Check for correct operation of cooling fan.

Let us know what you find please.

 

Its probably the thermostat, stuck partially open, due to an internal gasket that stretches and gets out of place, blocking the thermostat from closing.
That causes the engine to take longer than expected to warm up, resulting in the code being posted.
Since you have a 2007 XK (like mine), the thermostat housing is plastic and has been known to crack or break internally, so as a precaution it should be replaced when you replace the thermostat. You can buy the whole assembly (housing and thermostat) online, and do it yourself, if you are so inclined.

After you replace them, you may get another code (P0116) that can be cleared as noted in this thread:

https://www.jaguarforums.com/forum/x...solved-151085/

 

hey bro i got leaks on my coolant my water pump and few pipes were broken i repairs them all put a new water pump as well new coolant new pipes after a week now my car shows up code (p01280) code. which says (coolant thermostat) now what i have to do should i have to replace my thermostat, o2 sensor or what ?

 

Your profile says you have a 2016 XF. This is the X150 (XK, XKR) forum. If the codes mean the same, I'd replace the thermostat.