Technical Description of OBD-II Trouble Code
Range/Performance Issue with PCM/ECM/TCM Internal Temperature Sensor
What does that signify?
This is a generic diagnostic trouble code (DTC) for powertrain and is applicable to many OBD-II vehicles (1996-newer). This includes vehicles from Mazda, Honda, Dodge, Ford, BMW, VW, and others. Although it is a generic code, the specific repair steps may vary depending on the year, make, model, and powertrain configuration.
OBD-II trouble codes P0666, P0667, P0668, and P0669 are associated with the internal temperature sensor circuit of different modules. This circuit includes the Power Control Module (PCM), the Engine Control Module (ECM), and/or the Transmission Control Module (TCM).
The purpose of the PCM/ECM/TCM internal temperature sensor circuit is to monitor the temperature of various sensors housed within the control modules. Malfunctions are identified through control module self-test failures. In some vehicles, the three modules are integrated into one unit known as the PCM.
When the PCM, ECM, or TCM detects abnormal electrical signals within the internal temperature sensor circuit, code P0667 will be triggered and the check engine light or transmission warning lamp will illuminate.
An example of a TCM transmission control module:
What is the severity of this DTC?
The severity of this code can vary greatly, ranging from just an illuminated check engine light or transmission warning lamp in a vehicle that starts and runs, to a vehicle that may stall or not start at all. The seriousness of the code depends on the specific nature of the problem.
What are some of the symptoms of the code?
Symptoms of a P0667 trouble code may include:
What are some of the common causes of the code?
Possible causes for this P0667 code may include:
What are some P0667 troubleshooting steps?
The first step in troubleshooting any malfunction is to research the Technical Service Bulletins (TSB’s) specific to the vehicle’s year, model, and power plant. This can save a lot of time by providing guidance in the right direction.
The second step is to locate all the control modules within this circuit and visually inspect the associated wiring for obvious defects such as scraping, rubbing, bare wires, or burn spots. This inspection should also include ground straps and ground wires. Next, check the connectors for security, corrosion, and damaged pins. This process should include the PCM, ECM, and TCM based on the specific vehicle and control module configuration. The specific technical data for the vehicle will assist in locating components and understanding the control module configuration.
Advanced Steps
The advanced steps are highly vehicle-specific and require advanced equipment for accurate performance. These procedures involve using a digital multimeter and specific technical references for the vehicle. The technical data will include troubleshooting charts and the appropriate sequence to follow for an accurate diagnosis.
Voltage Checks
Specific troubleshooting guidelines must be referenced to determine the required voltage ranges for the various control modules. These references will include the pin numbers and voltage requirements associated with the PCM/ECM/TCM internal temperature sensor/circuit. Most control modules require a reference voltage of approximately 9 volts, although this may vary depending on the vehicle’s specific year and model.
If this process reveals the absence of a power source or ground, continuity testing may be necessary to check the integrity of the wiring, connectors, and other components. Continuity tests should always be performed with the power removed from the circuit, and normal readings for wiring and connections should show 0 ohms of resistance. Resistance or lack of continuity indicates faulty wiring that is either open or shorted and must be repaired or replaced. A continuity test from the various control modules to the frame will confirm the serviceability of ground straps and ground wires. The presence of resistance indicates a loose connection or possible corrosion.
What are some common repairs for this code?
Misdiagnosis often leads to the replacement of the PCM, ECM, or TCM when faulty wiring or loose connections are actually causing the code. Additionally, in vehicles equipped with two or more control modules, the wrong module may be replaced in error.
We always recommend seeking professional service to address this issue. However, if that is not possible, we offer the option to permanently delete this specific DTC. All other codes will continue to be addressed. If you are interested in this option, please upload your ECU file to our portal.
