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P037B Timing Reference High Resolution Signal A - Incorrect Signal

The OBD2 code P037B indicates that the engine control module (ECM) has detected an incorrect signal from the high-resolution timing reference signal A, which is used for precise timing of engine operations

Definition

The OBD2 code P037B indicates that the engine control module (ECM) has detected an incorrect signal from the high-resolution timing reference signal A, which is used for precise timing of engine operations

Common causes

  • Faulty crankshaft position sensor
  • Faulty camshaft position sensor
  • Damaged or corroded wiring/connectors
  • Timing belt/chain issues
  • Incorrectly installed or damaged timing components
  • Engine control module (ECM) malfunction
  • Signal interference from other components
  • Faulty ignition system components

Common misdiagnoses

  • Faulty crankshaft position sensor
  • Faulty camshaft position sensor
  • Timing chain/belt issues
  • Wiring or connector problems
  • Engine control module (ECM) failure
  • Incorrectly installed timing components
  • Fuel system issues
  • Ignition system problems
  • Vacuum leaks
  • Exhaust gas recirculation (EGR) system faults

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. This can provide more context and help identify related issues

  2. 2. Inspect Wiring and Connectors

    Visual Inspection: Check the wiring and connectors associated with the crankshaft and camshaft position sensors. Look for signs of damage, corrosion, or loose connections

  3. 3. Connector Condition

    Ensure that the connectors are clean and securely attached

  4. 4. Test the Sensors

    Crankshaft and Camshaft Sensors: Use a multimeter to test the resistance and output voltage of the crankshaft and camshaft position sensors. Compare the readings to the manufacturer’s specifications

  5. 5. Signal Testing

    If possible, use an oscilloscope to check the waveform of the signals from the sensors. This can help identify if the signal is weak or erratic

  6. 6. Check Timing Components

    Timing Belt/Chain: Inspect the timing belt or chain for wear or misalignment. A stretched or broken timing belt can cause timing issues

  7. 7. Timing Marks

    Ensure that the timing marks on the crankshaft and camshaft align correctly

  8. 8. Inspect the Engine Control Module (ECM)

    Software Updates: Check if there are any available updates for the ECM software that may address known issues

  9. 9. ECM Functionality

    If other troubleshooting steps do not resolve the issue, consider testing or replacing the ECM

  10. 10. Clear Codes and Test Drive

    After performing inspections and repairs, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code returns

  11. 11. Consult Technical Service Bulletins (TSBs)

    Look for any TSBs related to the specific make and model of the vehicle. Manufacturers may have issued guidance on common issues related to P037B

  12. 12. Professional Diagnosis

    If the issue persists after performing the above steps, it may be necessary to seek assistance from a professional mechanic or technician who has access to advanced diagnostic tools and equipment.Summary Troubleshooting OBD-II code P037B involves a systematic approach to inspect and test the relevant components, including sensors, wiring, and timing mechanisms. By following these steps, you can identify the root cause of the issue and take appropriate corrective action