Sensor Power Supply Circuit Low Voltage
The P06B4 code indicates that the Engine Control Module (ECM) has detected a low voltage condition on the 5-volt reference circuit that powers various sensors (e.g., throttle position, crankshaft position, camshaft position, etc.). This can be caused by a short to ground, a faulty sensor drawing excessive current, a damaged wiring harness, or a failing ECM. The low voltage disrupts sensor readings, leading to drivability issues.
01. Most Common Causes
- Short to ground in the 5-volt reference circuit
- Faulty sensor (e.g., throttle position sensor) causing excessive current draw
- Damaged wiring or connector corrosion
- Failing ECM (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine stalling or rough idle
- Reduced power or hesitation during acceleration
- Erratic transmission shifting
03. 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: Disconnect sensors one by one while monitoring the 5-volt reference voltage with a multimeter to isolate the short.
Step 4: If voltage returns to normal after disconnecting a sensor, replace that sensor.
Step 5: If no sensor is at fault, repair the wiring short or replace the ECM.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. Low sensor supply voltage can cause unpredictable engine behavior, stalling, or loss of power, which may lead to a crash.
How much does it cost to fix?▼
Typically $50-$150 for diagnosis and repair, but could be higher if the ECM needs replacement.