P0128
Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
P0128 is an OBD-II diagnostic trouble code meaning: Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature). Common causes: faulty thermostat, low coolant level. Estimated repair cost: $56–167.
Symptoms
- The engine takes a long time to warm up
- Increased fuel consumption
- Insufficient interior heating
- Reduced engine power
Causes
- Faulty thermostat
- Low coolant level
- Problems with the coolant temperature sensor
- Water pump malfunction
How to Fix
- Check coolant level
- Check thermostat operation
- Replace thermostat if necessary
- Check coolant temperature sensor
Related codes
Error P0128 by Vehicle Brand
FAQ
What does the P0128 code mean?
P0128 is an OBD-II diagnostic trouble code that indicates: Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
What causes a P0128 error code?
The most common causes of P0128 include: Faulty thermostat; Low coolant level; Problems with the coolant temperature sensor; Water pump malfunction.
How do I fix a P0128 diagnostic trouble code?
To fix P0128: Check coolant level. Check thermostat operation. Replace thermostat if necessary. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with P0128?
Limited driving only, diagnose soon
How much does it cost to fix P0128?
The estimated repair cost for P0128 is $56–167. Actual cost depends on your vehicle, location, and labor rates.
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