p0128
Moderate
Fiat · Cars
Coolant Thermostat (Coolant Temp Regulation) Malfunction
Quick Answer
Error code P0128 on your Fiat Cars means: Coolant Thermostat (Coolant Temp Regulation) Malfunction. This is usually fixable — see the step-by-step guide below.
Affected Models
Likely Causes
How to Fix It
1
Check coolant level and top off if necessary
2
Monitor coolant temperature with diagnostic scanner
3
Feel upper radiator hose for proper heating
4
Perform thermostat housing pressure test
5
Replace thermostat if stuck
Pro Tip
This fix requires some technical knowledge. If you're unsure about any step, consider contacting support or a qualified technician.
Parts You May Need
Thermostat assembly
Coolant
Gaskets
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