Hybrid Battery Voltage Sense Circuit Low
The P0B79 code indicates that the hybrid battery voltage sense circuit is reading a voltage lower than expected. This circuit monitors the voltage of the hybrid battery pack. A low reading can be caused by a faulty voltage sensor, wiring issues, or a weak battery cell. This condition can affect hybrid system operation and may lead to reduced performance or warning lights.
1. Symptoms You Will Notice
- Check hybrid system warning light
- Reduced fuel economy or performance
- Hybrid system may not operate properly
- Possible battery discharge or charging issues
2. Most Common Causes
- Faulty voltage sensor for hybrid battery block 'M'
- Short to ground in the detection circuit wiring
- Excessive resistance or loose connection in the sensor harness
- Damaged hybrid battery control module (BMS)
- Corrosion at battery or sensor connection terminals
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to retrieve all codes and freeze frame data.
Step 2: Inspect the hybrid battery voltage sensor and its wiring for damage or corrosion.
Step 3: Measure voltage at the sensor connector and compare to specifications.
Step 4: Test individual battery cells or modules for proper voltage.
Step 5: Replace the voltage sensor or repair wiring as needed.
4. 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 that could lead to loss of power or safety concerns.
How much does it cost to fix?▼
The cost typically ranges from $100 to $300 for diagnosis and repair, but can be higher if battery module replacement is needed.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.