P0379 - Timing Reference High Resolution Signal B No Pulses
The P0379 code indicates that the Powertrain Control Module (PCM) has detected a loss of signal from the high-resolution timing reference sensor B. This sensor is typically a crankshaft position sensor that provides precise timing data for fuel injection and ignition timing. The PCM expects a continuous pulse train from this sensor; when no pulses are received, it sets this code. This can cause the engine to run poorly or not start at all.
1. Most Common Causes
- Faulty crankshaft position sensor
- Wiring or connector issues (open, short, corrosion)
- Damaged reluctor ring or tone wheel
- PCM failure (rare)
2. Symptoms You Will Notice
- Engine cranks but does not start
- Engine misfires or runs rough
- Check Engine Light illuminated
- Reduced engine performance
3. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for additional codes.
Step 2: Inspect the crankshaft position sensor wiring and connector for damage, corrosion, or loose connections.
Step 3: Test the sensor's resistance and signal output with a multimeter or oscilloscope.
Step 4: Check the reluctor ring for damage or debris.
Step 5: If all else is fine, replace the crankshaft position sensor.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
No, it is not safe. The engine may stall or fail to start, leading to a breakdown.
How much does it cost to fix?▼
Typically $50-$150 for parts and labor, depending on the vehicle and sensor location.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.