What does fault code P064100 indicate?
2 Answers
Fault code P064100 refers to an open circuit in Sensor Reference Voltage A. Sensor Reference Voltage A refers to the 5V reference voltage provided internally by the engine control unit. If the sensor or the 5V reference voltage wiring harness is short-circuited to ground, the engine control unit's internal monitoring point detects 0V at this point, and the control unit will store the fault code for an open circuit in Reference Voltage A. The 5V reference voltage supplies power to multiple engine sensors via resistors and internal monitoring points. The internal resistor in the engine control unit serves to prevent damage to the control unit in case of a short circuit to ground in the sensor or 5V power supply.
I previously encountered this trouble code P0641 while driving, which indicates a sensor reference voltage circuit issue. The 5-volt reference voltage in the car may have a short circuit or open circuit. This causes the engine warning light to illuminate and affects the operation of other sensors, such as incorrect readings from the oxygen sensor or throttle position sensor, leading to sluggish acceleration, increased fuel consumption, or even stalling. I remember my car had this fault due to an aged and damaged wire, with symptoms like engine shaking after startup, which was fixed after inspection. I recommend using an OBD scanner to read the code immediately and avoid driving for too long to prevent further component damage. During regular maintenance, inspect the engine bay wiring harness to avoid friction wear or water ingress, which can reduce the likelihood of occurrence.
