P0373 critical

Timing Reference High Resolution Signal B Too Few Pulses

The P0373 code means the vehicle's onboard diagnostic system has detected: Timing Reference High Resolution Signal B Too Few Pulses. This is a critical severity code.

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Keep driving?
No -- stop driving
DIY difficulty
hard
Estimated cost
$100 - $700 (parts and labor)
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Common Symptoms

  • Check Engine Light on
  • Engine misfire or rough running
  • Possible no-start condition
  • Erratic idle

Probable Causes (Ranked by Likelihood)

  • Damaged camshaft position sensor reluctor Very High
  • Faulty camshaft position sensor B High
  • Wiring damage to cam sensor B Moderate
  • Timing chain stretch or jump Low

Step-by-Step Diagnostic Procedure

  1. Read cam sensor B waveform with oscilloscope for missing pulses.

  2. Inspect camshaft reluctor for damaged or missing teeth.

  3. Check cam sensor B air gap.

  4. Verify timing chain alignment marks.

Frequently Asked Questions

What is timing signal B?

Signal B typically refers to the Bank 2 camshaft position sensor. Engines with dual overhead cams or V-configuration engines have multiple timing signals.

Can a timing chain cause P0373?

Yes, a stretched or jumped timing chain can cause the camshaft reluctor to be out of position, generating incorrect pulse counts.

Is P0373 related to the crankshaft sensor?

No, P0373 is specific to the camshaft position signal. However, if the timing chain has jumped, both crank and cam sensor codes may appear.

Sources

This page is built from documented references. Verify against your own service info before repair work.

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