Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that the car's computer is having trouble reading the temperature inside itself. It's like when a thermometer isn't working right and you can't tell how hot or cold it is.
The P0666 code indicates an issue with the internal temperature sensor circuit in the vehicle's control module.
The control module, often referred to as the engine control unit (ECU), uses an internal temperature sensor to monitor its own operating temperature. The P0666 code is triggered when the ECU detects a malfunction in the sensor or its circuit, which could affect the module's ability to regulate engine performance and emissions.
• Check Engine Light is on
• Possible erratic engine performance
• Potential increase in emissions
• Faulty internal temperature sensor
• Wiring issues such as shorts or opens in the sensor circuit
• Malfunctioning control module
ECU: Engine Control Unit
OBD-II: On-Board Diagnostics II
• Scan for codes and check for any related codes
• Inspect the wiring and connectors related to the control module
• Test the internal temperature sensor for proper operation
• Repair or replace damaged wiring or connectors
• Replace the faulty internal temperature sensor
• Replace the control module if necessary
• OBD-II scanner
• Multimeter
• Basic hand tools
$200 - $800
Moderate
• Ford F-150
• Chevrolet Silverado
• Toyota Camry
• Regular vehicle maintenance
• Periodic inspection of wiring and connectors
• Using quality replacement parts
Sensor Issue
• Have the vehicle inspected by a professional if the Check Engine Light is on.
• Avoid ignoring the issue as it may lead to more serious problems.
Check with your vehicle manufacturer for specific warranty coverage related to the control module.
The P0666 code has been reported in various vehicle makes and models, typically related to sensor or wiring issues.
Moderate – It should be addressed soon to prevent potential engine performance issues.
Driving with a malfunctioning control module sensor may lead to increased emissions, which could be against local regulations.
• Vehicle at operating temperature
• Engine running
The control module is typically located in the engine bay or under the dashboard.
Q: Can I drive with a P0666 code?
A: While the car may still be drivable, it's best to address the issue to avoid potential engine performance problems.
Q: How is the P0666 code detected?
A: The vehicle's control module monitors its internal temperature sensor and sets the code when it detects a fault.
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