p0128
Easy Fix
Volvo · Sedans & Wagons
Coolant Thermostat Below Temp
Quick Answer
Error code P0128 on your Volvo Sedans & Wagons means: Coolant Thermostat Below Temp. 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 low
2
Monitor coolant temperature gauge behavior
3
Test thermostat operation by feeling radiator hoses
4
Replace thermostat if stuck open
5
Verify coolant temperature sensor resistance
Pro Tip
This is a common issue that most users can resolve without specialized tools. Try the first step before moving on to more complex solutions.
Parts You May Need
Thermostat
Coolant temperature sensor
Engine coolant
Radiator hoses
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