p0128
Moderate
Jeep · SUVs
Coolant Thermostat (Coolant Temp Regulation) Malfunction
Quick Answer
Error code P0128 on your Jeep SUVs 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
Monitor coolant temperature with scanner during warm-up
2
Check if temperature fluctuates abnormally
3
Inspect coolant level and condition
4
Feel radiator hoses for proper heat flow
5
Replace thermostat if it fails to regulate temperature
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 hoses
Engine coolant
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