P0370 medium Severity

P0370: Timing Reference High Resolution Signal 'A' Malfunction

Illuminated check engine light; possible rough idling, hesitation, misfiring, hard starting or no start, reduced power

Overview

P0370 indicates that the Powertrain Control Module (PCM) has detected a fault in the high resolution timing reference signal 'A', commonly generated by the crankshaft or camshaft position sensors, affecting engine timing and ignition/fuel control.

Common Symptoms

  • Check engine light illuminated
  • Rough or uneven idle
  • Intermittent misfire or hesitation during acceleration
  • Engine hard to start or no-start condition
  • Reduced engine power or decreased fuel efficiency

Most Common Causes

Faulty crankshaft position sensor high

Crank sensor failing to produce a valid high-resolution timing signal is one of the most frequent triggers for P0370.

Damaged or corroded wiring/connectors in the timing reference signal circuit high

Open, shorted, corroded, or loose wiring can interrupt the high-resolution reference signal to the PCM.

Faulty reluctor wheel or timing wheel (missing/damaged teeth) medium

Damage to the reluctor/trigger wheel can alter the signal timing or amplitude.

PCM/ECM internal fault or software/calibration issue medium

Rare, but possible if sensor and wiring test good and signal remains unreadable.

Incorrect sensor installation or improper gap low

Improper mounting or incorrect air gap can distort the signal waveform.

Diagnostic Steps

  1. Connect an OBD-II scanner and verify the presence of P0370 and related codes (e.g., P0335, P0340).
    Expected: Scanner confirms P0370 stored and any related position sensor circuit codes.
    Interpretation: Code presence indicates timing reference signal malfunction; related codes can pinpoint specific sensor circuits.
  2. Visually inspect crankshaft/camshaft position sensors and harness for damage, corrosion, or loose connections.
    Expected: No visible cuts, corrosion, or loose pins in wiring/connectors.
    Interpretation: Damaged wiring or connectors often cause signal loss; repair before further testing.
  3. Measure sensor output with a multimeter or oscilloscope per OEM specs (resistance for CKP; signal waveform while cranking).
    Expected: Resistance within spec and clean signal waveform present.
    Interpretation: Out-of-spec resistance or erratic waveform indicates sensor or circuit failure.
  4. Verify reference voltage and ground at sensor connector with ignition on.
    Expected: 5V reference (Hall sensor) and good ground present.
    Interpretation: Lack of reference or ground indicates wiring or PCM output issue.
  5. Check reluctor wheel or timing components for missing/damaged teeth and proper alignment.
    Expected: Reluctor wheel intact with correct tooth profile and alignment.
    Interpretation: Damaged or misaligned timing components distort sensor signals.
  6. If sensors and wiring are verified good but issue persists, consider PCM diagnostic/testing by specialist.
    Expected: PCM inputs correctly interpret signals or exhibit internal fault.
    Interpretation: Internal PCM faults require repair or replacement.

Repair Solutions

Replace faulty crankshaft position sensor medium
Estimated Cost: $100 - $400

Sensor cost and labor vary by vehicle; common and effective fix when sensor fails.

Repair or replace damaged wiring and connectors medium
Estimated Cost: $50 - $300

Includes harness repair, connector cleaning, and securing grounds.

Repair/replace reluctor wheel or timing components hard
Estimated Cost: $200 - $1500

Timing component repairs vary widely; may require mechanical work and timing system removal.

Reflash or replace PCM/ECM hard
Estimated Cost: $500 - $1500

Used when internal PCM faults or corrupted calibration cause signal misinterpretation.

Common Misdiagnoses

Avoid these common diagnostic mistakes:

  • Replacing the crankshaft position sensor without checking wiring/connectors
  • Assuming misfire codes are primary cause rather than secondary to timing signal issues
  • Ignoring related position sensor codes that clarify root cause

Frequently Asked Questions

What does the P0370 code mean?

Timing Reference High Resolution Signal 'A' Malfunction is the standard definition for P0370. This diagnostic code is triggered when the ECU detects a problem in the Ignition.

Should I stop driving if I have P0370?

With a severity level of medium, illuminated check engine light; possible rough idling, hesitation, misfiring, hard starting or no start, reduced power

Symptoms associated with DTC P0370

The most typical signs are: Check engine light illuminated, Rough or uneven idle, Intermittent misfire or hesitation during acceleration.

What causes the P0370 code?

Potential culprits include: Faulty crankshaft position sensor, Damaged or corroded wiring/connectors in the timing reference signal circuit, Faulty reluctor wheel or timing wheel (missing/damaged teeth). A proper diagnosis is recommended.

Repair cost breakdown for P0370

It depends on what needs to be fixed. Repair or replace damaged wiring and connectors repairs are cheaper (~$300), while Reflash or replace PCM/ECM repairs are on the higher end (~$1500).

Does P0370 affect Ford, Toyota, or Honda?

This is a universal code. You might see P0370 on Ford, Chevrolet, Toyota, Honda, Nissan, or any other OBD-II vehicle.

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