Hybrid Battery Voltage Sense Circuit Low
The P0B51 code indicates that the hybrid battery voltage sense circuit is reading lower than expected. This circuit monitors the voltage of the hybrid battery pack. A low reading can be caused by a faulty battery voltage sensor, damaged wiring or connectors, or a weak hybrid battery. This condition can affect the hybrid system's ability to charge and discharge properly, potentially leading to reduced fuel economy and performance.
01. Most Common Causes
- Faulty hybrid battery voltage sensor
- Damaged or corroded wiring/connectors in the voltage sense circuit
- Weak or failing hybrid battery pack
- Open or short circuit in the voltage sense circuit
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced fuel economy
- Hybrid system warning message on dashboard
- Possible loss of hybrid assist or power
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to retrieve all codes and freeze frame data.
Step 2: Visually inspect the hybrid battery voltage sensor and its wiring for damage or corrosion.
Step 3: Test the voltage sense circuit for proper voltage and continuity using a multimeter.
Step 4: Compare sensor readings with known good values; replace sensor if out of spec.
Step 5: If sensor and wiring are okay, test the hybrid battery pack capacity and health.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code as it may indicate a serious hybrid battery issue. Driving could lead to reduced performance or complete loss of hybrid function.
How much does it cost to fix?▼
The cost to fix P0B51 typically ranges from $150 to $400, depending on whether the sensor or wiring needs repair. Hybrid battery replacement is more expensive.