P0379 medium Severity

P0379: Timing Reference High Resolution Signal B No Pulses

Check engine light may illuminate; engine may be hard to start, run rough, stall, or exhibit poor performance due to loss of precise timing reference.

Overview

P0379 indicates the engine control module detects no pulses from the timing reference high-resolution signal B, often related to engine position sensor circuit issues affecting ignition timing and engine performance.

Common Symptoms

  • Check engine light illuminated
  • Difficulty starting or no start
  • Rough idle or misfires
  • Reduced engine performance

Most Common Causes

Faulty engine position sensor (crankshaft or camshaft) high

Sensor may fail to generate pulses; high-resolution signal loss triggers code.

Wiring issues (open/shorted harness, connector corrosion) high

Signal interruption between sensor and PCM can cause no pulses.

Reluctor wheel/trigger disc damage or misalignment medium

Damaged or misaligned trigger can prevent correct pulse generation.

PCM internal fault or signal processing error medium

PCM timing circuit failure or internal damage may falsely detect no pulses.

Diagnostic Steps

  1. Connect OBD-II scanner and confirm P0379 code, check for related codes.
    Expected: P0379 present; possible additional codes indicating timing or sensor issues.
    Interpretation: Validates issue and identifies if other codes may influence diagnosis.
  2. Visually inspect engine position sensor wiring and connectors for damage or corrosion.
    Expected: No breaks, corrosion, or loose connectors.
    Interpretation: Damage in wiring/connector likely cause if issues found.
  3. Test the engine position sensor output signal using a multimeter or oscilloscope while cranking.
    Expected: Fluctuating voltage or waveform pulses.
    Interpretation: No pulses indicates sensor failure or circuit interruption.
  4. Check continuity and reference voltage between sensor and PCM.
    Expected: Good continuity and correct reference voltage.
    Interpretation: Lack of reference or open circuit suggests wiring or PCM issues.
  5. If wiring and sensor test normal, evaluate PCM internal timing capture circuit or consider reprogramming.
    Expected: PCM provides correct signal processing.
    Interpretation: PCM fault likely if previous components are good.

Repair Solutions

Replace faulty engine position sensor medium
Estimated Cost: $150 - $350

Crankshaft or camshaft sensor replacement often resolves missing signal pulses.

Repair or replace damaged wiring/connectors medium
Estimated Cost: $50 - $200

Fixing harness faults restores signal integrity.

Repair or replace PCM hard
Estimated Cost: $600 - $1200

Required if internal PCM timing circuitry is confirmed faulty; professional programming often required.

Common Misdiagnoses

Avoid these common diagnostic mistakes:

  • Assuming general misfire codes without verifying timing reference signal
  • Replacing unrelated sensors such as MAP or MAF instead of position sensor

Frequently Asked Questions

What does the P0379 code mean?

The P0379 code stands for Timing Reference High Resolution Signal B No Pulses. This generally indicates an issue with the Ignition system.

Reflecting on severity: How bad is P0379?

This is a medium priority issue. Check engine light may illuminate; engine may be hard to start, run rough, stall, or exhibit poor performance due to loss of precise timing reference.

Symptoms associated with DTC P0379

The most typical signs are: Check engine light illuminated, Difficulty starting or no start, Rough idle or misfires.

What causes the P0379 code?

The most common causes are: Faulty engine position sensor (crankshaft or camshaft), Wiring issues (open/shorted harness, connector corrosion), Reluctor wheel/trigger disc damage or misalignment.

Estimated repair costs for different causes of P0379

The cost varies significantly based on the root cause. For example, replacing a Repair or replace damaged wiring/connectors typically costs between $50 and $200, while fixing a Repair or replace PCM can range from $600 to $1200.

Is the P0379 code specific to Ford?

Yes, P0379 is a generic code that applies to all OBD-II compliant vehicles, including Ford, Toyota, Honda, Chevrolet, Nissan, Dodge, BMW, and more.

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