p0128
Moderate
Lexus · Sedans
Coolant Thermostat Malfunction
Quick Answer
Error code P0128 on your Lexus Sedans means: Coolant Thermostat Malfunction. This is usually fixable — see the step-by-step guide below.
Affected Models
Likely Causes
How to Fix It
1
Check coolant level and condition
2
Inspect coolant hoses
3
Test engine temperature sensor
4
Feel radiator hose temperatures
5
Replace thermostat if needed
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 housing
Coolant
Gasket sealer
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