2019 Nissan Maxima P0128 Engine Coolant Temperature

2019 Nissan Maxima


  • 3.5L V6 Engine
  • Horsepower: Approximately 300 hp
  • Torque: Approximately 261 lb-ft


  • Continuously Variable Transmission (CVT)

Fuel Economy:

  • The EPA estimated fuel economy is around 20 MPG city and 30 MPG highway.

Understanding and Addressing the P0128 Code in your 2019 Nissan Maxima

Modern vehicles feature an array of sensors and systems designed to ensure optimal performance and efficiency. One such system is the Engine Control Module (ECM), which constantly monitors various parameters to ensure the engine is functioning correctly. The P0128 code is a diagnostic trouble code (DTC) that can appear on the dashboard of a 2019 Nissan Maxima, indicating an issue with the engine’s coolant temperature.

What is the P0128 Code?

The P0128 code is a generic code that is present in most vehicles, including the 2019 Nissan Maxima. It specifically points to a problem with the coolant temperature being below the expected operating range as defined by the manufacturer. In the case of the 2019 Nissan Maxima, this typically means that the engine isn’t reaching its proper operating temperature within a certain time frame after starting.


Common Causes of the P0128 Code

Several factors can trigger the P0128 code in a 2019 Nissan Maxima:

  • Faulty Thermostat: A thermostat that’s stuck open or opening too soon can prevent the engine from reaching the proper operating temperature.

A vehicle’s Thermostat plays a crucial role in maintaining optimal engine temperature and overall performance. It remains closed when the engine is cold, allowing it to quickly warm up for efficient combustion. Once the engine reaches the designated temperature, the thermostat opens. This allows coolant circulation to cool down the engine and prevent overheating.

  • Faulty Engine Coolant Temperature (ECT) Sensor: The ECT Sensor provides the ECM with information about the engine’s temperature. A malfunctioning sensor can result in inaccurate readings and trigger the code.
Coolant Temp Sensor

The vehicle’s Coolant Temperature Sensor plays a vital role in monitoring the temperature of the engine’s coolant fluid. Installed within the engine’s cooling system, this sensor measures the temperature of the coolant. It sends real-time coolant temperature data to the engine control unit (ECU). The ECU uses this information to adjust various parameters of the engine’s operation, such as fuel injection timing, air-fuel mixture, and fan speed.

  • Coolant Level: Insufficient coolant or low coolant levels can hinder the engine’s ability to heat up properly.
  • Coolant Leaks: Any coolant leaks within the cooling system can disrupt the heating process, leading to the code.
  • Faulty Radiator Fan: If the radiator fan isn’t working as intended, it might not cool the engine down efficiently, preventing it from reaching the optimal temperature.

Effects of the P0128 Code

While the P0128 code might not immediately result in drastic consequences, ignoring it can lead to long-term issues. An engine that consistently operates below its intended temperature can suffer from reduced fuel efficiency, increased emissions, and increased wear and tear on engine components. It can also impact the performance and overall longevity of the vehicle.

Diagnosing and Resolving the P0128 Code

  1. Check Coolant Levels: Begin by verifying that the coolant levels are within the manufacturer’s recommended range.
  2. Inspect for Leaks: Examine the cooling system for any signs of leaks, such as puddles of coolant under the vehicle.
  3. Test the Thermostat: The thermostat’s function can be checked by monitoring the engine’s temperature as it warms up. If it doesn’t reach the optimal temperature within a reasonable time, the thermostat might need replacement.
  4. Inspect the ECT Sensor: If the ECT Sensor is faulty, it should be replaced to ensure accurate temperature readings.
  5. Check Radiator Fan: Ensure that the radiator fan is working properly and kicks in at the right temperature.
  6. Perform a Diagnostic Scan: If you cannot identify the issue, we recommend having a professional mechanic conduct a diagnostic scan using specialized tools to accurately pinpoint the problem.

The P0128 code in a 2019 Nissan Maxima indicates an issue with the engine’s coolant temperature not reaching the expected operating range. While it might not cause immediate breakdowns, addressing this issue promptly is crucial to maintain the vehicle’s performance and efficiency. By diagnosing and resolving the causes of the P0128 code, you can ensure your 2019 Nissan Maxima avoids potential long-term damages. If you’re unsure about the diagnosis or lack automotive expertise, it’s always best to consult a qualified Nissan mechanic to accurately diagnose and fix the issue.

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