p0128
Moderate
Mazda · SUVs & Crossovers
Coolant Thermostat (Coolant Temp Not Reaching Normal Operating Temp)
Quick Answer
Error code P0128 on your Mazda SUVs & Crossovers means: Coolant Thermostat (Coolant Temp Not Reaching Normal Operating Temp). 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 up if low
2
Monitor coolant temperature with scanner
3
Feel upper radiator hose for warmth
4
Perform thermostat housing inspection
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
Gasket set
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