P0652 Sensor Reference Voltage “B” Circuit Low

P0652 code definition

A P0652 code means that a malfunction has been identified in the sensor reference voltage "B" circuit, and this has most likely been done by the powertrain control module or another of the control modules related to the system.

What the P0652 code means

A generic OBD-11 code, the P0652 means that the "B" area of a circuit (rather than a specific wire or component) has a fault, and that the PCM or another control module has detected it. The modules that might do this range widely and can include the alternative fuel control, ABS, body, instrument panel, turbo, fuel injection, anti-theft, traction, cruise control, proximity alert, or climate control modules, among others.

What causes the P0652 code?

The P0652 code can be cause by:

• Internal problems with the PCM
• Open or shorted wiring and/or connectors between two or more control modules
• Open or shorted wiring and/or connectors in the PCM's input circuitry (typically from the engine's sensors)
• Disconnected or loose ground wires to one of the control modules

What are the symptoms of the P0652 code?

In addition to the storing of the code, the P0652 code has a few common symptoms that include an engine that begins to run very roughly, difficulty starting the engine (or no starting at all), a distinct decrease in fuel economy, misfires in the engine, a check engine light, and low amounts of operating power in the vehicle.

How does a mechanic diagnose the P0652 code?

A mechanic will diagnose the P0652 code using an OBD-II scanner along with some visual inspections. The first step is for the mechanic to examine the freeze frame data and determine just when the code first appeared. They must then reset the fault codes and do a road test to see if it triggers the code to reappear.

They will then do a visual examination of the connectors and wiring associated with the "B" circuit. They will look for any disconnected, shorted or corroded wiring and components, including fuses. If everything appears to be in good order, they can move on to the repair process. If not, they must do any and all repairs or replacements and then retest the vehicle to see if the code is still occurring. If so, they can then move on to repairs.

Common mistakes when diagnosing the P0652 code

Because this particular code involves a wide range of potential issues, it is important to heavily assess the stored codes alongside any symptoms. Often, mechanics look at the codes as the cause of the problem, allowing them to make unneeded repairs.

How serious is the P0652 code?

The P0652 code can cause a vehicle to reach a no start condition. It can make the engine run very inconsistently and roughly, and it can gobble up fuel. The vehicle may struggle to accelerate or have power adequate to the driver's needs, and so it is a very serious matter.

What repairs can fix the P0652 code?

Unfortunately, the most common repairs for the P0652 are time consuming and demand a lot of diagnosis and troubleshooting:

• First, the mechanic must use the scanner to verify the code, and then reset the fault codes before performing the road test and looking at the data upon returning to the shop. If the P0652 remains, they must do the visual inspection of the wiring. *The mechanic must look for damaged, open or disconnected wiring related to the "B" circuit and then do the necessary repairs.
• This code relates to several drivability sensors, and each is part of the controller area network or CAN bus that must be evaluated using a specialized scanner. You cannot manually test the thousands of pins on the CAN bus, but a scanner will be able to show the operations of the control modules and the pin values.
• Using the CAN scanner to diagnose the circuitry problems, determine which portions of the "B" circuit need repair or replacement. Do the repairs and retest with the scanner to see if the code has been cleared.

Additional comments for consideration regarding the P0652 code

This code is referring to a five volt signal from or to multiple engine drivability sensors. The sensors speak directly to control modules that operate various systems in the vehicle. While it is possible for individual control modules to fail, it is rare. This issue is typically due to wiring problems.

Need help with a P0652 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.