What is the P0642 fault number? What is the Sensor Reference Voltage “A” Circuit Low error code description? How do I fix the P0642 fault code What are the causes and symptoms of the P0642 error code?
What is the P0642 fault code? What does it signify?
P0642 is a code that indicates the signal from the reference voltage circuit “A” detected by the powertrain controller module (PCM), or related control modules, is lower than the manufacturer’s specifications. This fault may be caused by many modules such as climate control module and distance proximity module.
The P0642 fault codes are set when the PCM and control modules mention above detect that any of the sensors’ voltage signals is too low. Circuit “A” refers to circuits which supply voltage to sensors that are associated with the differential, transmission, or driveline. Circuit “B” is about sensors that control the engine or drive functions. You should note that many sensors are interrelated in both circuits, so faults in the “A” circuit will affect all subsystems and sensors. This code often comes with a sensor fault code that indicates which sensor has failed. P0642 that does not set itself may indicate a problem with the PCM program or software.
NOTE: Hall-effect sensors are not dependent on a reference voltage. They generate their own signal currents using a magnetic field. This code does not affect such sensors.
P0642 fault codes can be found on vehicles made by Ford, Kia and Suzuki as well as Audi, Mercedes-Benz-Benz-Hybrid, Hyundai, Volkswagen or Duramax.
What is the P0642 Fault Code and Why Does It Happen?
Below are some reasons to set fault code P0642:
- – Broken, melted or corroded cables or connectors connecting control modules to the PCM.
- Blown fuse
- – Power relay for defective system
- – Short circuits in engine sensors caused by cables or electrical components
- – A poor electrical connection or ground wire in the PCM input circuit
- – Defective engine sensor(s)
- – Defective PCM
What are the symptoms for P0642 Malfunction Code
You may experience the following symptoms if your vehicle has the code P0642:
- – Illumination at the check engine lights
- – The engine might not start or run well.
- – An increase in fuel consumption
- – Reduced engine performance
- Engine misfires
- – Transmissions may not shift into gear properly or may have difficulty shifting between them.
- – The transmission is unable to switch between economy and sport modes
- – The transmission cannot switch between two-wheel and four-wheel drive modes.
- Transmission is not shifting from low to high gear
- – Front or centre differentials might not engage
- Faulty speedometer/odometer not working or not working
How to Fix the P0642 Fault Code
Other codes may appear in the PCM when the communication problem between control modules is encountered. These codes are usually caused by faulty connections, code P0642.
The following repairs may be able to resolve the P0642 fault code:
- Repair or replace any damaged, disconnected, corroded or shorted components, connectors, and wiring to the modules and PCM.
- – Replacing blownfuses
- – Replacement and detection of defective sensors
- – All defective control modules replaced
- – Replacing the defective PCM
You must reprogramme any control module that you need to replace. After a few driving cycles, it is likely that you will encounter many fault codes if your mechanic has not programmed the module. A poorly programmed PCM could prevent your vehicle from starting.
You should also clear fault code 00642 and test the system again after every repair. This helps to identify the root cause of failure and allows for correct repair.
How serious is the P0642 fault code?
The fault code P0642 should be reported to the manufacturer immediately. Faults in communication between control modules could cause engine performance to drop and affect vehicle drivability. To keep your vehicle running, you must fix fault code P0642 as soon as possible.
