AutoCodes – BMW – P0128 BMW

P0128 BMW Code - Thermostat Low Coolant Temperature

Quick Answer

Indicates that the thermostat monitor has not achieved the required engine operating temperature within a specified amount of time after starting the engine. Common causes include Leaking or stuck open thermostat, Low engine coolant level, Insufficient warm up time. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0128 BMW indicates Thermostat Low Coolant Temperature .
Common causes: Common causes include Leaking or stuck open thermostat, Low engine coolant level, Insufficient warm up time.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 73,985

How popular is this code, among other codes? Medium

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jun 14, 2020

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0128 BMW Description

Indicates that the thermostat monitor has not achieved the required engine operating temperature within a specified amount of time after starting the engine.

OBDII Code P0128 BMW - Thermostat Low Coolant Temperature - AutoCodes.com — P0128 BMW Code - Thermostat Low Coolant Temperature

What does this mean?

What are the Possible Causes of the DTC P0128 BMW?

Leaking or stuck open thermostat
Low engine coolant level
Insufficient warm up time
Faulty engine coolant temperature sensor
Engine coolant temperature sensor harness is open or shorted
Engine coolant temperature sensor circuit poor electrical connection

How to Fix the DTC P0128 BMW?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

If cooling system is not leaking and the fluid level is OK, replacing the thermostat usually takes care of the problem.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0128 BMW code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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Need Help with the Code?

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0128 BMW Code

1. What are common symptoms of OBDII code P0128 in a BMW related to a low coolant temperature thermostat?

The common symptoms include the engine running cooler than normal, a slow-to-warm-up engine, poor fuel economy, and potential heater performance issues.

2. What are the possible causes of OBDII code P0128 in a BMW?

The most common causes are a faulty thermostat, a malfunctioning coolant temperature sensor, low coolant levels, a stuck open thermostat, or issues with the radiator fan.

3. How can I diagnose the OBDII code P0128 in my BMW?

You can diagnose the code by checking the coolant level, inspecting the thermostat for proper operation, testing the coolant temperature sensor, and ensuring the radiator fan is functioning correctly.

4. Can I still drive my BMW with OBDII code P0128?

It is not recommended to drive your BMW with this code for an extended period as it can lead to reduced engine efficiency and potential overheating issues. It is best to address the problem promptly.

5. How do I repair OBDII code P0128 in my BMW?

The repair typically involves replacing the thermostat, checking and replenishing the coolant levels, testing and possibly replacing the coolant temperature sensor, and ensuring proper operation of the radiator fan.

6. Is it possible to reset the OBDII code P0128 in my BMW without fixing the underlying issue?

While clearing the error code may temporarily turn off the check engine light, it is crucial to address the root cause to prevent further damage to the engine and maintain optimal performance.

7. What can happen if I ignore OBDII code P0128 in my BMW?

Ignoring this code can lead to decreased fuel efficiency, potential engine overheating, increased emissions, and possible long-term damage to engine components.

8. Can a DIY enthusiast fix OBDII code P0128 in a BMW?

Depending on your skill level and access to tools, DIY enthusiasts can tackle the repair for this code. However, if you are unsure or inexperienced, it is advisable to seek professional assistance.

9. How long does it take to repair OBDII code P0128 in a BMW?

The repair time can vary based on the exact cause and complexity of the issue. Typically, it can take anywhere from 1 to 3 hours to diagnose and repair the problem.

10. Are there any preventive measures to avoid OBDII code P0128 in a BMW?

Regular maintenance, including checking coolant levels, inspecting the thermostat, and ensuring the cooling system is functioning correctly, can help prevent issues leading to this error code.