P0128 Moderate Powertrain

Coolant Temperature Below Thermostat Regulating Temperature

Common Causes

Failed thermostat stuck open
Faulty ECT sensor reading too low
Air pocket in coolant system

Common Symptoms

Hard Start Engine Overheating White Exhaust Smoke Poor Fuel Economy

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Quick Info

Code P0128
System Powertrain
Severity Moderate

Disclaimer

This information is for diagnostic guidance only. Always verify repairs with a qualified technician before performing safety-critical work.

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