What Is the P0651 Code?
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The P0651 error code definition is “Sensor Reference Voltage “B” Circuit/Open.” Every vehicle relies on several sensors to check on various processes within the vehicle in question. Your vehicle’s Powertrain Control Module (PCM) or Engine Control Module (ECM) utilizes dozens and sometimes hundreds of sensors throughout the vehicle to ensure it functions correctly. This code will indicate that reference voltage B has some kind of fault in the reference circuit.
More About the P0651 Code
A reference signal is important to ensure that other circuits function correctly. An engine sensor typically receives a 5-volt reference signal from the electrical connection in the PCM, which it changes to a specific voltage signal to create specific readings when returned to the PCM. This ensures that the process whereby the signals are sent and received is working, helping to create accurate sensor readings. This trouble code points to a problem with the reference voltage signal for circuit “B,” specifically that there is either a generic signal error or the circuit is open. This generic powertrain code will appear in many OBD-II-equipped vehicles. But the specific circuit defined as “B” will vary by vehicle, so you should check the information for your specific make and model to ensure you have the right one.
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What Are the Symptoms of a P0651 Code?
The P0651 fault code is very generic, and the “B” circuit can potentially connect to any vehicle component. Your symptoms will likely vary depending on your vehicle’s make and model. Because codes in this arena usually have to do with the engine and transmission, those are the most likely places to see symptoms. The most common symptoms include reduced fuel efficiency, general drivability issues, and lack of engine power. You’ll usually see the check engine light also turn on in all vehicles.
What Are Some Causes of a P0651 Code?
Again, to determine the causes of the P0651 diagnostic trouble code, you must know which circuit is malfunctioning and why. It’s most common for this code to happen due to a malfunctioning or faulty sensor, but problems such as bad or blown fuses and fusible links are also very common. In some cases, the circuit itself might also develop problems, with faulty wiring harnesses, poor connections, and damaged wires commonly appearing. It’s also possible for the problem to lie with the PCM or other faulty control modules. But it’s almost always because of a PCM programming error, as a failing PCM is extremely uncommon.
How Serious Is the P0651 Code?
As with the cause, the severity of your P0651 engine code will have to do with the impacted sensor circuit and the underlying cause. To determine the severity of the code, you’ll need to check for other stored codes using a scan tool, which can help you understand the underlying cause. Consider this type of code very serious, as it’s more likely to cause problems if you underestimate how severe the code is rather than overestimate how severe it is.
Can I Still Drive with a P0651 Code?
Because OBD-II code P0651 could be serious, you should avoid driving when it’s active. This code could be surprisingly serious. If the underlying cause is severe, you might damage the vehicle and the engine more if you continue driving it. That can be expensive and difficult to find a fix for. Once you notice the check engine light on your vehicle turn on, you should stop driving and learn more about what the code means.
How Easy Is It to Diagnose a P0651 Code?
P0651 is extremely generic, which means there’s not a lot of information to go off. Generic codes require more investigation to determine the core problem, which isn’t always true with other codes. To determine the core problem, you should use specialty tools, technical vehicle information sources, and experience with your type of vehicle. An experienced mechanic will have the specialized tools to perform the diagnostic procedure, test for the correct voltage and crankshaft position, and determine the core problem.
How Difficult Is It to Inspect a P0651 Code?
Just like with diagnosis, inspection for a P0651 sensor code is often difficult. Because this is a generic code, the code definition doesn’t give you much insight into the core problem. You’ll need to know what possibilities are associated with the code, but you’ll also need to understand which are most and least likely, so you know what to look at first. Specialty equipment, a vehicle diagnostic scanner, and information from technical service bulletins are all very helpful. Because this is so complex, talking to a knowledgeable mechanic is best before setting off on your own.
Need Additional Help with Your P0651 Code?
The P0651 code is a hard code to untangle. If you need extra help with your P0651 code, you can find an expert who can help you fix the problem without making common mistakes that plague DIYers.
Start with information about an auto repair shop in your area. Because you’ll likely want to avoid driving with the P0651 code active, a local automobile repair shop can be a huge help.
Other stored codes are usually an important part of ensuring you know what’s happening. The OBD-II database, available at KBB.com, will give you insight into all sorts of codes, including how to handle them when they arise.
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