P0379 — Timing Reference High Resolution Signal “B” No Pulses #

Note: The wording of this code may differ depending on the vehicle manufacturer (OEM).

• Timing Reference High Resolution Signal “B” No Pulses (GM, Ford, Chrysler)
• High-Res Timing Reference Signal B Missing (Toyota)
• No Signal Detected on High Resolution Reference B (Honda)
• Crankshaft Position Reference Signal B No Pulses (BMW)

Summary of DTC P0379 #

The P0379 diagnostic trouble code (DTC) indicates that the engine control module (ECM) or powertrain control module (PCM) has not detected any pulses from the high-resolution timing reference signal “B”. This signal typically comes from a crankshaft or camshaft position sensor, which relays precise rotational information. The absence of this signal can disrupt fuel injection and ignition timing, impacting engine performance. The code is often triggered by sensor failure, wiring issues, or problems with the reluctor wheel. Accurate diagnosis is crucial to avoid misfires, stalling, or no-start conditions. Addressing P0379 promptly helps maintain your engine’s reliability and safety.

Common Symptoms for DTC P0379 #

When P0379 is present, drivers and technicians may notice a range of performance issues, often linked to timing irregularities. Symptoms vary based on the severity of the signal loss and the specific vehicle’s system design. Common signs include:

• Difficulty starting the engine
• Engine misfires or rough running
• Reduced power and acceleration
• Intermittent or complete engine stalling
• Illuminated check engine light (MIL)
• Poor fuel economy

Most Likely Causes for DTC P0379 #

The causes behind a P0379 code typically relate to electrical or mechanical faults in the timing reference circuit. Some are simple and quick to fix, while others require more in-depth inspection. The most frequent causes are:

1. Faulty high-resolution timing sensor (crankshaft or camshaft position sensor failure)
2. Damaged, corroded, or loose wiring/connectors in the sensor circuit
3. Failed reluctor wheel or missing teeth (the trigger wheel attached to the crankshaft or camshaft)
4. PCM/ECM software or internal failure (less common, but possible)
5. Incorrect sensor installation or misalignment
6. Blown fuse or power supply issue to the sensor

Step-by-Step Diagnostic for DTC P0379 #

Diagnosing P0379 requires a methodical approach to avoid misdiagnosis and unnecessary parts replacement. Always start with the basics and proceed to more complex checks as needed. Here’s a recommended sequence:

• 1. Visually inspect the sensor and wiring for damage, corrosion, or loose connections.
• 2. Check for other related DTCs that could point to a shared circuit or component issue.
• 3. Use a scan tool to monitor live data from the timing sensor; look for missing or irregular signals.
• 4. Measure sensor voltage and resistance per the OEM service manual to verify function.
• 5. Inspect the reluctor wheel for missing or damaged teeth, debris, or misalignment.
• 6. Test the sensor circuit continuity from the sensor connector back to the PCM/ECM.
• 7. If all else checks out, consider PCM/ECM reprogramming or replacement as a last resort.

Possible Repairs for DTC P0379 #

Once the root cause is identified, repair options focus on restoring the integrity of the timing reference system. Always use OEM parts where possible for reliability. Typical repairs include:

• Replacing the high-resolution timing sensor (crankshaft/camshaft position sensor)
• Repairing or replacing damaged wiring/connectors
• Cleaning or replacing the reluctor wheel
• Securing or re-aligning the sensor if improperly installed
• Replacing a blown fuse or repairing the sensor’s power supply
• Updating or replacing the PCM/ECM if internal faults are present

Is It Safe to Drive with P0379? #

Driving with a P0379 code is NOT recommended. The absence of a high-resolution timing signal can cause unpredictable engine operation, sudden stalling, and loss of power, especially under acceleration or load. While some vehicles may limp along in a reduced-power mode, you risk engine damage or being stranded. It’s best to diagnose and repair this issue promptly.

Vehicles Most Commonly Affected by P0379 #

While P0379 can potentially appear on any OBD-II compliant vehicle, it is more frequently reported on certain makes and models, particularly those with advanced timing control systems. Models with known occurrences include:

• Chevrolet Silverado, Malibu, Trailblazer
• Ford F-150, Focus, Explorer
• Chrysler 300, Pacifica, PT Cruiser
• Toyota Camry, Tundra
• Honda Accord, CR-V
• BMW 3 Series, 5 Series

Common Mistakes & Best Practices for P0379 #

Misdiagnosis or overlooking simple faults is common with timing-related codes. Following best practices can save time and money:

• Assuming the sensor is always at fault—wiring and connectors are just as likely to fail.
• Neglecting to inspect the reluctor wheel for physical damage or debris.
• Skipping live data analysis—a scan tool can reveal intermittent signal loss invisible to the naked eye.
• Replacing parts without confirming the root cause wastes money and may not solve the problem.
• Always verify repairs by clearing the code and performing a road test to ensure the issue is resolved.

Quick FAQ for P0379 #

Still have questions about P0379? Here are answers to the most common concerns:

• Q: Can a dead battery cause P0379?
  A: A dead battery alone is unlikely to trigger P0379, but low system voltage can exacerbate underlying sensor or wiring issues.
• Q: Will replacing the timing sensor always fix P0379?
  A: Not always—if the wiring, reluctor wheel, or PCM/ECM is at fault, replacing the sensor alone will not resolve the code.

If you’re unsure about diagnosing or repairing P0379, consult a qualified technician or your vehicle’s OEM service manual for detailed guidance. Addressing timing reference issues promptly helps keep your engine running at its best and avoids more costly repairs down the line.