Technical Description of OBD-II Trouble Code
The PCM/ECM/TCM Internal Temperature Sensor B Range/Performance
What does that signify?
This is a generic powertrain diagnostic trouble code (DTC) that 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 P06AB, P06AC, P06AD, and P06AE are associated with the internal temperature sensor “B” circuit of different modules. This circuit includes the Power Control Module (PCM), the Engine Control Module (ECM), and/or the Transmission Control Module (TCM). To determine which is the “B” circuit in your particular case, refer to a vehicle-specific repair guide.
The purpose of the PCM/ECM/TCM internal temperature sensor “B” 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 automobiles, the three modules are integrated into one consolidated unit known as the PCM.
When the PCM, ECM, or TCM detects abnormal electrical signals within the internal temperature sensor “B” circuit, code P06AC will be set and the check engine light or the 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 a transmission warning lamp on 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 P06AC trouble code may include:
What are some of the common causes of the code?
Causes for this P06AC code may include:
What are some P06AC troubleshooting steps?
The first step in the troubleshooting process for any malfunction is to research the Technical Service Bulletins (TSB’s) for the specific vehicle by year, model, and power plant. This can save a lot of time in the long run by providing guidance in the right direction.
The second step is to locate all of the control modules within this circuit and perform a thorough visual inspection to check the associated wiring for obvious defects such as scraping, rubbing, bare wires, or burn spots. This process must also include ground straps and ground wires. Next, check the connectors for security, corrosion, and damaged pins. This process must include the PCM, ECM, and the TCM based on the specific vehicle and the control module configuration. The specific tech data for the automobile will assist with component location and the control module configuration.
Advanced Steps
The advanced steps are highly vehicle-specific and require the appropriate advanced equipment to perform accurately. These procedures require a digital multimeter and the specific technical references for the vehicle. Specific 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 voltage ranges required for the various control modules. These references will include the pin numbers and the voltage requirements associated with the PCM/ECM/TCM internal temperature sensor/circuit. Most control modules require a reference voltage of approximately 9 volts, although voltage requirements may vary based on the specific year and model of the vehicle.
If this process identifies the absence of a power source or ground, continuity testing may be required 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 the normal readings for wiring and connections should be 0 ohms of resistance. Resistance or no continuity indicates faulty wiring that is open or shorted and must be repaired or replaced. A continuity test from the various control modules to the frame will confirm the serviceability level 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 may result in replacing the PCM, ECM, or TCM when faulty wiring or loose connections are causing this code. Also, on vehicles equipped with two or more control modules, the wrong module may be replaced in error.
We always recommend seeking professional service to resolve 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.
