Technical Description of OBD-II Trouble Code
Performance Issue in Internal Control Module Torque Calculation
What is the meaning of this?
This generic powertrain diagnostic trouble code (DTC) is commonly found in many OBD-II vehicles, including Mazda, Ford, Mercedes Benz, Chevy, and others.
When the code P061B is stored, it indicates that the powertrain control module (PCM) has detected an internal performance error in the engine torque monitoring system. Other controllers may also detect an internal PCM performance error in the engine torque monitoring system, leading to the storage of a P061B code.
Internal control module monitoring processors are responsible for various self-test duties and overall accountability of the control module. The PCM and other related controllers constantly monitor the input and output signals of the engine torque calculation system. The engine torque monitoring system also interacts with the transmission control module (TCM), traction control module (TCSM), and other controllers.
The PCM and other controllers monitor engine torque using input signals from the mass air flow (MAF) sensor and the accelerator pedal position (APP) sensor (also known as the pedal position sensor). The desired or approximate required engine torque is calculated using the APP sensor, while the actual engine torque is calculated using data from the MAF sensor.
Whenever the ignition is on and the PCM is powered, self-tests for internal engine torque monitoring are initiated. In addition to running internal controller self-tests, the controller area network (CAN) also compares signals from each individual module to ensure proper functioning of all controllers. These tests are performed simultaneously.
If the PCM detects a discrepancy between the desired torque and actual torque (more than 50-Newton meters for more than 1 second) with the engine RPM above 5,000 RPM and volumetric efficiency greater than 16 percent, a code P061B will be stored and a malfunction indicator lamp (MIL) may illuminate. Depending on the perceived severity of the malfunction, multiple failure cycles may be necessary for MIL illumination.
Photo of a PCM with the cover removed:
How severe is this DTC?
Codes related to internal control module processors should be considered severe. A stored code P061B could result in sudden and unexpected drivability and fuel efficiency issues.
What are some of the symptoms of the code?
Symptoms of a P061B trouble code may include:
What are some of the common causes of the code?
Possible causes for this code may include:
What are some troubleshooting steps for P061B?
Diagnosing a code P061B can be challenging, even for experienced technicians. Reprogramming may also be necessary for controller replacement. Without the proper reprogramming equipment, it is impossible to replace a defective controller and complete a successful repair.
If there are ECM/PCM power supply codes present, they should be addressed before attempting to diagnose a P061B. Additionally, if there are MAF/APP sensor or throttle position sensor (TPS) codes present, these should be diagnosed and repaired first.
Follow the manufacturer’s recommendations for testing MAF, APP, and TPS sensors. The oscilloscope can be particularly useful when testing APP and TPS sensors. Replace any failed components as needed.
Before declaring an individual controller defective, several preliminary tests can be performed. A diagnostic scanner, a digital volt/ohmmeter (DVOM), and reliable vehicle information are necessary. An oscilloscope may also be helpful.
Connect the scanner to the vehicle diagnostic port and retrieve all stored codes and freeze frame data. Record this information in case the code is intermittent. After recording the information, clear the codes and test drive the vehicle until the code is reset or the PCM enters readiness mode. If the PCM enters readiness mode, the code is intermittent and will be more difficult to diagnose. If the code is reset, continue with the following preliminary tests.
When diagnosing a P061B, information is crucial. Search for technical service bulletins (TSB) that match the stored code, vehicle information (year, make, model, and engine), and exhibited symptoms. The right TSB may provide diagnostic information that can greatly assist in the diagnosis.
Use the vehicle information source to obtain connector face views, connector pin-out charts, component locators, wiring diagrams, and diagnostic flow charts related to the code and vehicle in question.
Use the DVOM to test controller power supply fuses and relays. Test and replace any blown fuses as needed. Fuses should be tested with the circuit loaded.
If all fuses and relays appear to be functioning properly, visually inspect the controller-related wiring and harnesses. Also check the chassis and engine ground junctions. Use the vehicle information source to find ground locations for related circuits. Use the DVOM to test ground integrity.
Visually inspect system controllers for signs of water, heat, or collision damage. Any damaged controller, especially due to water, should be considered defective.
If the controller power and ground circuits are intact, suspect a defective controller or a controller programming error. Controller replacement will require reprogramming. In some cases, reprogrammed controllers may be available through aftermarket sources. Other vehicles/controllers will require on-board reprogramming that can only be done through a dealership or other qualified source.
