Hybrid Battery Voltage Sense Circuit Range/Performance
The P0B73 code indicates that the hybrid battery voltage sense circuit is reporting a voltage reading outside the expected range or performance parameters. This circuit monitors the voltage of the hybrid battery pack to ensure proper charging and discharging. A fault can be caused by a failing hybrid battery, a faulty voltage sensor, wiring issues, or a problem with the battery control module. This code is common in hybrid vehicles and can lead to reduced fuel economy, loss of hybrid assist, or a no-start condition.
1. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced fuel economy
- Loss of hybrid system assist or power
- Vehicle may not start or enter limp mode
2. Most Common Causes
- Faulty battery voltage sensor L (internal to the HV battery pack)
- Open circuit, short to ground, or short to positive in the sensor L wiring
- Corroded, loose, or damaged connectors in the voltage sensor L harness
- Severe cell/module imbalance in the group monitored by sensor L
- Internal failure of the hybrid battery ECU (HVBECU)
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to retrieve all stored codes and freeze frame data.
Step 2: Visually inspect the hybrid battery voltage sensor wiring and connectors for damage, corrosion, or loose connections.
Step 3: Test the voltage sensor output using a multimeter and compare to manufacturer specifications.
Step 4: Check the hybrid battery pack voltage and individual cell voltages for imbalance or degradation.
Step 5: If wiring and sensor are okay, test the battery control module for proper operation.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code as it can lead to reduced performance, potential stalling, or damage to the hybrid battery. Have the vehicle inspected as soon as possible.
How much does it cost to fix?▼
The cost varies depending on the root cause. A simple sensor replacement may cost $50-$150, while hybrid battery replacement can be $1,000-$3,000 or more.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.