What Does P0652 Mean?
The 5-volt sensor reference voltage circuit 'B' is reading lower than the expected specification. The ECM has detected that the voltage on this shared reference line has dropped below the normal 4.9-5.1V threshold, which means sensors on this circuit are receiving insufficient reference voltage and reporting inaccurate readings. The driver may notice rough idle, poor throttle response, stalling, or the engine entering limp mode.
Safety Warning
Multiple engine sensors may be reporting inaccurate data, causing unpredictable engine behavior including stalling or sudden power loss. The engine may enter limp mode. Avoid highway driving and have the vehicle repaired immediately.
Common Causes
35%
A sensor on the 'B' reference circuit has failed internally and is shorting the 5V line to ground
25%
Wiring short to ground in the 5V reference 'B' circuit (chafed wire touching chassis/engine ground)
20%
Corroded connector allowing moisture to create a path to ground on the reference circuit
15%
ECM internal 5V reference regulator degradation (sagging output)
5%
Excessive electrical load on the reference circuit from additional aftermarket sensors
Diagnostic Steps
1
With key on engine off, measure the 5V reference at each sensor on the 'B' circuit. Identify which sensors share this reference line from the wiring diagram. A reading well below 4.9V confirms the fault.
2
Disconnect all sensors on the 'B' reference circuit one at a time. After each disconnection, check if the reference voltage recovers to 5V. If it does, the last disconnected sensor has an internal short to ground.
3
If the voltage remains low with all sensors disconnected, inspect the harness for chafing, especially where it routes near sharp metal edges, hot exhaust components, or through body grommets.
4
With all sensors disconnected, measure from the 5V reference wire to chassis ground with the multimeter set to resistance. Any reading under 10K ohms indicates a short to ground in the harness.
5
If the harness is clean and no short exists, measure the reference voltage at the ECM output pin. A low reading at the ECM itself (with sensors disconnected) indicates internal ECM regulator failure.
Estimated Repair Cost
$75 - $900
Parts + labor, varies by vehicle and location
The 5-volt sensor reference voltage circuit 'B' is reading lower than the expected specification. The ECM has detected that the voltage on this shared reference line has dropped below the normal 4.9-5.1V threshold, which means sensors on this circuit are receiving insufficient reference voltage and ...
The most common cause of P0652 (Sensor Reference Voltage "B" Circuit Low) is: A sensor on the 'B' reference circuit has failed internally and is shorting the 5V line to ground
Typical repair costs for P0652 range from $75 to $900, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Multiple engine sensors may be reporting inaccurate data, causing unpredictable engine behavior including stalling or sudden power loss. The engine may enter limp mode. Avoid highway driving and have the vehicle repaired immediately.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0652 to identify the root cause.
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Quick Info
Category
Powertrain
System
Engine Sensor Reference Voltage
Difficulty
Type
Generic (SAE)
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