P0652 Code: Sensor Reference Voltage “B” Circuit Low

The engine relies on inputs from many sensors to ensure its efficient operation. These sensors send a voltage signal to the powertrain control module (PCM), which allows the computer to monitor and operate various systems. The PCM also supplies a reference voltage to the sensors. If the PCM detects an issue with one of the sensor reference voltage circuits, which, in this case refers to a circuit designated as “B,” on-board diagnostics will log a P0652 code.

What Does the P0652 Code Mean?

Diagnostic trouble code P0652 stands for “Sensor Reference Voltage “B” Circuit.”

Sensors are responsible for monitoring key functions like ignition timing, fuel delivery, charging output, transmission shifting, and emission controls, among others.

If one or more sensors are defective, the vehicle can experience problems like being unable to go into closed loop (coolant or oxygen sensor), receiving incorrect fuel mixture (throttle position sensor, manifold absolute pressure sensor, or airflow sensor), and more.

A typical, three-wire sensor has a reference wire, a signal wire, and a ground wire. The PCM supplies the sensor with a 5-volt reference voltage. Then, the sensor alters that voltage according to operating conditions and sends a corresponding signal back to the PCM.

Usually, several sensors share the same 5-volt reference voltage circuit. If the PCM detects a problem with the reference voltage circuit designated “B”, it will set code P0652.

Note: The definition of code P0652 might be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.

What are the Common Causes of the P0652 Code?

• Faulty engine sensor or another component on the “B” reference voltage circuit
• Wiring issues
• Powertrain control module failure or software in need of an update

What are the Common Symptoms of the P0652 Code?

• Illuminated check engine light
• One or more sensors don’t operate properly, potentially leading to a variety of driveability problems

How to Diagnose the P0652 Code

DTC P0652 is a generic powertrain code that can be logged in vehicles with an OBD-II system. However, keep in mind that the steps for diagnosis and repair can vary, depending on vehicle specifications.

Diagnosing a trouble code such as this one might require you to use a scan tool or inspect the engine for signs of damage, which can be tricky for someone who’s not well-versed in automotive repair. Under this circumstance, it’s best to have a certified mechanic work on your vehicle instead.

But if you think you have the skills to do the job on your own, here’s a video you might want to check out before proceeding.

How to Fix the P0652 Code

Without the right tools and automotive expertise, attempting to fix a P0652 code can be frustrating and confusing. It can even lead to more damage if done incorrectly. To ensure that all steps and protocols are followed correctly, it’s best to have a trained professional perform the necessary repairs.

But if you think your DIY skills are enough to get the job done on your own, make sure to have the right equipment before you start. Keep in mind that there’s no umbrella fix that will resolve all trouble codes for every make and model, so having the right manual is crucial in ensuring a successful repair job. Before you begin, you might want to check out guides like those from Chilton or an ALLDATA subscription to get vehicle-specific repair information.