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P0666 Fault-Error Code PCM-ECM-TCM Internal Temperature Sensor Circuit

Updated: 6 days ago

What is P0666 Fault/Error Code?

 

The P0666 Fault-Error Code indicates a problem with the interior temperature sensor circuit of the vehicle's control modules such as the power control module (PCM), engine control module (ECM), and/or transmission control module (TCM). This code is detected and recorded by the vehicle's OBD-II (On-Board Diagnostics II) system.




 

PCM/ECM/TCM Internal Temperature Sensor Circuit is located within the vehicle's control modules such as the power control module (PCM- Powertrain Control Module), engine control module (ECM- Engine Control Module) and/or transmission control module (TCM- Transmission Control Module). defines a sensor circuit. This circuit is designed to detect and monitor the internal temperature of modules.



P0666

 

This sensor circuit allows the internal temperature to be monitored by the control module and to respond to temperature changes. This helps modules optimize operating temperature and ensure proper performance. It can also contribute to the protection of modules in extreme temperature situations.

 

The PCM/ECM/TCM Interior Temperature Sensor Circuit is an important component that ensures the proper functioning of the vehicle's power and engine management systems. Any malfunction in this circuit may result in improper operation of control modules or deterioration in vehicle performance.

 



The P0666 fault code is usually caused by a malfunction or defect in this sensor circuit. This malfunction can be caused by a variety of reasons, including a short circuit in the temperature sensor, an open circuit, an electrical connection problem, or a malfunction of the sensor itself.

  



What are the symptoms of P0666 Fault/Error Code?

 

Symptoms associated with fault/error code P0666 may include:

 

Malfunction Lamp Turns On: The vehicle's engine control unit (ECU) may turn on the fault lamp when it detects the P0666 fault code. This gives the driver a warning that there is a problem with the interior temperature sensor circuit.

 



Reduced Engine Performance: A problem with the interior temperature sensor circuit can affect the vehicle's performance. Symptoms may include engine feeling weak, decreased acceleration power, or erratic engine operation.

 

Reduced Fuel Economy: A problem in the interior temperature sensor circuit can affect the regulation of the fuel-air mixture. This may result in a decrease in the vehicle's fuel economy.

 

Shifting Problems: If the transmission control module (TCM) indicates a problem with the interior temperature sensor, shifting problems may also occur. This may manifest itself with symptoms such as delays or jerks in gear shifting.

 



Problems in Other Systems: A malfunction in the PCM/ECM/TCM interior temperature sensor circuit can also affect other electronic systems of the vehicle. These may include the air conditioning system, electronic control systems and other related systems.

 

What could be the causes of P0666 Fault/Error Code?

 

There are various factors that can cause the P0666 malfunction/error code to appear. These factors may include:

 

Interior Temperature Sensor Malfunction: The vehicle's PCM/ECM/TCM interior temperature sensor may be faulty. The sensor itself may have a short circuit, open circuit, or other electrical or mechanical problem that causes the sensor to not function properly.

 



Electrical Connection Problems: There may be problems with the electrical connections in the internal temperature sensor circuit. Looseness in wiring, corrosion, or short circuits may prevent the sensor circuit from functioning properly.

 

PCM/ECM/TCM Malfunction: The vehicle's power control module (PCM), engine control module (ECM) or transmission control module (TCM) may be faulty. A malfunction in any of these modules may affect the correct operation of the internal temperature sensor.

 



Improperly Applied Software Update: An incorrectly applied software update on the vehicle's control modules can cause problems with the interior temperature sensor circuit.

 

Physical Damages: Physical damages inside the vehicle, such as water or moisture leaking into the sensor, may cause damage to the interior temperature sensor.

 

Electrical Component Malfunctions: General malfunctions in the vehicle's electrical system may cause the interior temperature sensor circuit to malfunction or malfunction.

 



What Steps Should Be Followed to Resolve the P0666 Fault/Error Code?

 

The following steps can be followed to solve the P0666 fault/error code:

 

Diagnostics: As a first step, a diagnostic should be performed to diagnose potential problems with the vehicle's interior temperature sensor circuit. This means performing an OBD-II (On-Board Diagnostics II) fault scan of the vehicle and using appropriate diagnostic equipment to determine the root cause of the fault.

 

Checking the Internal Temperature Sensor: The internal temperature sensor and its connection parts should be checked. The physical condition of the sensor should be inspected and checked for any damage, corrosion or other problems. If necessary, the sensor should be replaced.

 



Checking Electrical Connections: All electrical connections in the internal temperature sensor circuit should be reviewed. Cable connections and ports should be inspected and problems such as loose connections, corrosion or short circuits should be identified. If such problems are found, the links should be fixed.

 

PCM/ECM/TCM Check: The vehicle's power control module (PCM), engine control module (ECM), or transmission control module (TCM) should be inspected and checked if necessary. Modules may need to be reprogrammed or replaced if necessary to ensure proper functioning.

 



Repair or Replacement: After the diagnostic process, faulty parts may need to be repaired or replaced. This may include replacing the interior temperature sensor, electrical connections, or control modules.

 

System Testing and Verification: After all repairs have been made, it is important to subject the vehicle to a system test and confirm that the interior temperature sensor circuit is functioning properly.

 



These steps are the basic steps that can be followed to solve the P0666 fault code. However, since every vehicle and every situation is different, it is important to consult an auto service or mechanical professional when you receive this fault code on your vehicle.

 

What are the Long-Term Effects of the P0666 Fault/Error Code?

 

Long-term effects of fault/error code P0666 may include:

 

Reduced Engine Performance: A problem with the interior temperature sensor circuit can affect the vehicle's engine performance. The engine may lose power, have difficulty accelerating, or operate erratically. This may negatively affect the daily driving experience of the vehicle.

 



Increased Fuel Consumption: A problem with the interior temperature sensor circuit can prevent the vehicle's fuel-air mixture from being adjusted properly. This may cause an increase in fuel consumption, so the driver may have to spend more fuel.

 

Increase in Exhaust Emissions: When the vehicle's fuel-air mixture is not adjusted correctly, exhaust emissions may increase. This could increase the vehicle's environmental impact and cause it to fail to comply with emissions regulations.

 



Long-Term Damage: A problem in the internal temperature sensor circuit can put undue stress and wear on other engine components. Over time, this can cause other parts of the engine to become damaged and cause the engine to need further repairs or replacement.

 

Driving Safety Risk: Decrease in engine performance or irregular operation may make it difficult for the driver to control the vehicle and endanger driving safety. This can pose a risk, especially in situations requiring sudden acceleration or maneuvering.

 



Fault code P0666 should be taken seriously and resolved as soon as possible. It is important for the safety, performance and long-term durability of the vehicle. If a vehicle with a fault code shows any signs of malfunction, it is important to consult a car service or mechanical specialist.

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