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P0115 Code – What Does It Mean & How To Fix It

This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.


In the area of vehicle diagnostics, trouble codes serve as an essential indication of potential problems within a vehicle’s system. One such code that relates to the engine temperature diagnostic signal circuit is P0115 DTC Trouble Code. It is crucial that you understand the effects of P0115 so as to be able to identify and diagnose underlying problems with your vehicle’s performance.


The P0115 code indicates that the engine’s Coolant Temperature indicator circuit has malfunctioned. Control of engine temperatures is the responsibility of an ECT sensor, which transmits this data to a control module for engines. In order to ensure optimum performance and maximum fuel efficiency, the ECU shall use these data for the adjustment of different engine parameters.


The P0115 error code may be caused by a number of different things:

  • A defective ECT sensor: Over time, the ECT sensor may degrade or grow imprecise, giving false indications of the temperature.
  • Wire Problems: Signal transmission might be hampered by corroded or damaged wire that connects the ECT sensor to the ECM.
  • Connector issues: Corroded or loose connectors might prevent the ECT sensor and ECM from properly communicating.
  • Coolant Level: The accuracy of the ECT sensor may be impacted by insufficient engine coolant or a cooling system leak.
  • ECM Malfunction: In a small percentage of situations, the Engine Control Module itself may be to blame for the P0115 error code.


When the P0115 code is triggered, you may observe various symptoms indicating potential issues with your vehicle:

  • Illuminated Check Engine Light: The most apparent sign of a trouble code, the check engine light is activated.
  • Problems with engine performance: Due to inaccurate temperature measurements, the engine may have reduced power, hesitancy, or poor acceleration.
  • Excessive heating or cooling: If the engine temperature gauge fluctuates wildly, there might be a cooling system issue.
  • Poor Fuel Efficiency: Fuel efficiency might be decreased by using fuel-to-air ratios that are not optimally calculated due to incorrect temperature data.


A methodical strategy is needed to correctly identify the P0115 code’s root cause. The following diagnostic procedures can be carried out by a skilled mechanic or an OBD-II scanner:

  • Checking for Codes: The P0115 code may be read and retrieved from the vehicle’s ECM using an OBD-II scanner.
  • Visual Inspection: To find any obvious problems, the ECT sensor, it’s wiring, and its connections must be thoroughly inspected visually.
  • Testing the ECT Sensor: The resistance and voltage output of the sensor should be measured with a multimeter in order to evaluate its performance.
  • Checking Coolant Level and System: To make sure the cooling system and coolant level are within the acceptable limit, the technician will examine them.

Common mistakes

Some typical errors can happen during diagnostics and repairs, resulting in inaccurate or inefficient fixes:

  • Ignoring wire and Connectors: A loose connector or broken wire is frequently the cause of problems but is frequently disregarded.
  • Replacing the ECT Sensor Without Testing: Before contemplating a replacement, the sensor’s operation must be properly tested.
  • Ignoring Cooling System Issues: Cooling system problems should be resolved since they may affect the readings from the ECT sensor.

How serious is this?

The seriousness of the P0115 code is influenced by various factors. Although this may seem like a small inconvenience, it is possible that engine performance issues, decreased fuel efficiency, and the possibility of damage over time can arise if an issue has not been resolved. In order not to experience additional complications, timely diagnosis and treatment are recommended.

What repairs can fix the code?

repair manuals

The following remedies can be made if the P0115 code’s underlying cause has been found:

  • Replacement of the ECT Sensor: If the sensor is broken, a suitable and superior replacement should be used.
  • Fixing wires and connections: If required, damaged wires or connections should be fixed or replaced.
  • Fixing Cooling System Issues: Any leaks in the cooling system or issues with the coolant level should be fixed right away.

Related codes

Occasionally, other DTCs might accompany the P0115 code, providing additional insights into related issues. Commonly related codes include P0116 (Engine Coolant Temperature Circuit Range/Performance Problem) and P0117 (Engine Coolant Temperature Circuit Low Input).


The P0115 DTC code appears to indicate that there may be a circuit problem with the engine temperature sensor. You may be able to effectively address this problem by understanding its meaning, causes, symptoms, and appropriate treatment. 

Swift diagnosis and proper fixes will not only clear the code but also ensure your vehicle operates optimally, leading to a smoother and more reliable driving experience. In order to ensure the best condition of your vehicle, you must always contact a competent automotive specialist for precise diagnosis and safe repairs.

P0115 Code – What Does It Mean & How To Fix It