P06B1 - Sensor Power Supply Circuit Low
The P06B1 code indicates that the Engine Control Module (ECM) has detected a low voltage condition on the 5-volt reference circuit that supplies power to various sensors, such as the throttle position sensor, crankshaft position sensor, or manifold absolute pressure sensor. This can be caused by a short to ground, a faulty sensor, or a damaged wiring harness. The ECM monitors the voltage on this circuit and sets the code when it falls below a specified threshold, typically around 4.5 volts.
1. Most Common Causes
- Short to ground in the 5-volt reference circuit
- Faulty sensor drawing excessive current
- Damaged wiring or connectors
- Corroded or loose electrical connections
- Failed ECM (rare)
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine stalling or rough idle
- Poor acceleration or hesitation
- Reduced fuel economy
- Other sensor-related codes may be present
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to retrieve all codes and freeze frame data.
Step 2: Visually inspect the wiring and connectors for damage, corrosion, or loose connections.
Step 3: Measure voltage at the 5-volt reference circuit with a multimeter; should be around 5 volts with key on.
Step 4: Disconnect sensors one by one while monitoring voltage; if voltage returns to normal, the last disconnected sensor is likely faulty.
Step 5: Check for shorts to ground by measuring resistance between the reference circuit and ground.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code as it can cause engine stalling, poor performance, and potential damage to other components. Have the vehicle diagnosed and repaired promptly.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for diagnosis and repair, depending on the cause. Replacing a faulty sensor may cost $20-$100, while wiring repairs can be $50-$150.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.