p0128
Moderate
Infiniti · Sedans
Coolant Thermostat (Coolant Temp. Malfunction)
Quick Answer
Error code P0128 on your Infiniti Sedans means: Coolant Thermostat (Coolant Temp. Malfunction). This is usually fixable — see the step-by-step guide below.
Affected Models
Applies to all models
Likely Causes
How to Fix It
1
Check coolant level and top off if needed
2
Monitor coolant temperature with scanner
3
Test thermostat by observing temperature rise
4
Replace thermostat if stuck open or closed
5
Inspect water pump for proper operation
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 and gasket
Coolant temperature sensor
Coolant
Water pump seal
Related Error Codes