p0128
Moderate
Porsche · Sedans & Sports Cars
Coolant Thermostat (Coolant Temp Regulation) Malfunction
Quick Answer
Error code P0128 on your Porsche Sedans & Sports Cars means: Coolant Thermostat (Coolant Temp Regulation) 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 up if necessary
2
Inspect for coolant leaks in hoses, gaskets, and radiator
3
Measure engine coolant temperature with a scan tool during warm-up
4
Feel radiator hoses for temperature changes
5
Replace thermostat if it fails to reach normal operating 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
Thermostat housing gasket
Coolant hoses
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