How much does it cost to fix P0128?

Typical repair cost is $50–$300.

P0128 — Coolant Thermostat — Temperature Below Regulating Temp

Low Severity · Cooling

OBD-II code P0128 means your vehicle's ECU detected: Coolant Thermostat — Temperature Below Regulating Temp. Below: causes, step-by-step fixes, and repair cost — free, no signup needed.

Low severity — safe to drive in most cases. Clear the code and monitor. If it returns, have it inspected.

Typical Repair Cost

$50–$300

Parts + labor, national average

Severity

Low

Monitor — low urgency

🔍

Common Causes of P0128

Stuck-open thermostat (most common)
Faulty ECT sensor
Low coolant level

🔧

How to Fix Code P0128

Replace thermostat ($50–$200 parts+labor)

Test coolant temperature sensor ($30–$100)

Check for coolant leaks

❓

FAQ — Code P0128

What does OBD-II code P0128 mean?

P0128 means your vehicle's onboard computer detected: Coolant Thermostat — Temperature Below Regulating Temp. This is a low-severity code in the Cooling category.

How much does it cost to fix code P0128?

Typical repair cost for P0128 is $50–$300 including parts and labor. Costs vary by vehicle make, model, and location. A free scan at AutoZone or O'Reilly is a good first step.

Can I drive my car with code P0128?

Code P0128 is low severity. In most cases you can drive normally, but clear the code and monitor whether it returns.

What are the most common causes of P0128?

The most common causes are: Stuck-open thermostat (most common), Faulty ECT sensor, Low coolant level. Always start with the cheapest diagnosis step before replacing parts.

Will code P0128 clear itself?

Code P0128 will clear itself after the underlying issue is fixed and the ECU completes several successful drive cycles. Clearing it without fixing the root cause only masks the problem temporarily.

Is P0128 showing on your car?

Enter your VIN for a free vehicle-specific report — recalls, specs, and market value. No signup required.

🔗

Related Cooling Codes

P0115Engine Coolant Temperature Sensor Circuit P0116Engine Coolant Temperature Sensor Range/Performance P0117ECT Sensor Low Voltage P0118ECT Sensor High Voltage P0125Insufficient Coolant Temperature for Closed...P0480Cooling Fan 1 Control Circuit...

OBD-II code data is based on SAE J2012 standards and general repair industry data. Repair costs are national averages and vary by vehicle, location, and shop. Always consult a qualified mechanic for a diagnosis specific to your vehicle.