How to resolve the P0651 fault code?
3 Answers
P0651 fault code applies to all car manufacturers, meaning Sensor Reference Voltage B Circuit/Open fault. It is recommended to check the data stream of each sensor and inspect the wiring for aging or breakage, and repair any faults immediately upon discovery. The following is a related introduction: The fault code appears when the Electronic Control Unit (ECU) detects an error in the 5-volt reference voltage circuit B. Possible causes include a short circuit or open circuit in the 5-volt reference voltage circuit to a sensor, short circuit or open circuit in one or more sensors, automatic transmission hydraulic sensor failure, solenoid valve failure, transmission control module failure, transmission input speed (RPM) sensor failure, transmission output speed (RPM) sensor failure, etc.
I'm a seasoned driver with over 30 years of experience. When the P0651 fault code appears, indicating that the sensor reference voltage is too low, it's usually caused by a short circuit in the sensor wiring or a blown fuse. In such a situation, I would first turn off the engine, find a safe place to park, open the hood, and manually inspect the sensor connector. I'd use a multimeter to check if the voltage is around 5V. If a multimeter isn't handy, I'd simply check the fuse box for any blown fuses and replace them if necessary. If there's any damage to the wiring, it needs to be properly reconnected. If I can't fix it myself, I'd drive to a professional repair shop and have the mechanic use a diagnostic computer to check it, to avoid prolonged neglect affecting engine fuel consumption and safety. During regular maintenance, periodically cleaning dust from the wiring harness can also help reduce such faults.
As someone who loves DIY car repairs, I have a simple process for dealing with P0651 code: First, use an OBD scanner to confirm the fault, then focus on checking the wiring from the sensor to the computer module. Loose connectors need to be re-secured, and the fuse should be replaced with a new one from the labeled slot in the engine compartment fuse box. Sometimes, large temperature changes can cause wiring to age and short-circuit, which is a common issue, so I keep some electrical tape handy to wrap the wires myself. A low-cost approach is to refer to the repair manual to locate the sensor and test it. If all else fails, then take it to a shop. This saves time and money while also allowing you to learn. Remember to check if the warning light is on before parking each time—early detection can prevent breakdowns on the road.
