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p0128
Moderate
SEAT · SUVs & Crossovers
Coolant Temperature Regulation Malfunction
Quick Answer
Error code P0128 on your SEAT SUVs & Crossovers means: Coolant Temperature Regulation Malfunction. This is usually fixable — see the step-by-step guide below.
Affected Models
Applies to all models
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Likely Causes
  1. Stuck-open thermostat allowing coolant to circulate without proper heating
  2. Faulty engine coolant temperature (ECT) sensor
  3. Broken water pump impeller reducing coolant circulation
  4. Cooling fan continuously running due to failed cooling system switch
  5. Low coolant level affecting temperature regulation
How to Fix It
1
Monitor the ECT sensor reading and observe if coolant heats up properly
2
Check coolant level and refill if necessary with proper coolant type
3
Feel the upper and lower radiator hoses to detect proper coolant flow
4
Test thermostat operation by observing engine warm-up time
5
Replace thermostat if coolant temperature fails to reach normal operating range
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
Engine coolant temperature sensor
Water pump
Engine coolant
Thermostat housing gasket
Related Error Codes
P0171P0300P0420P0411P0441
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