P0652 indicates that the Powertrain Control Module (PCM) has detected a low voltage condition on the Sensor Reference Voltage B circuit, which supplies a stable reference voltage to several sensors.
Corroded connectors, broken wires, or loose terminals can cause the reference voltage to drop below specification.
A sensor that draws reference voltage (e.g., MAP, MAF, O2) with an internal short or failure can pull the circuit low.
The internal regulator that creates the reference voltage may be defective, resulting in insufficient voltage.
A poor ground connection in the circuit can cause voltage loss and trigger the code.
Only after ruling out wiring, sensor, and regulator problems should a PCM defect be considered.
Replacing the PCM is rarely the correct solution. The code is almost always caused by wiring, grounding, or a faulty sensor/regulator. Only consider PCM replacement after all other possibilities have been eliminated.
Yes. A low reference voltage can affect the operation of sensors that rely on that voltage, leading to rough idle, stalling, or reduced power.
It can be intermittent if the problem is a loose connector or intermittent ground. However, many vehicles will store the code once the voltage drops below the threshold, even if the condition resolves later.
After correcting the fault, clear the code with a scan tool and drive the vehicle through a complete drive cycle to verify that the code does not return.