Ignition

P0323 — Engine Speed Input Circuit Intermittent

Severity: medium Drive with care, to a shop

What P0323 means

The engine control unit relies on a speed signal, usually from the crankshaft position sensor or distributor pickup, to know engine RPM and time spark and fuel. P0323 sets when that signal drops out or becomes erratic from time to time. Because the fault is intermittent, it may show up only when the engine is hot or vibrating, or at certain RPM.

Symptoms

  • Check Engine light on
  • Rough or hunting idle
  • Intermittent stalling
  • Hesitation or stumbling on acceleration
  • Loss of power
  • Hard or inconsistent starting
  • Tachometer needle jumping or dropping to zero

Possible causes

  1. Failing or heat-sensitive crankshaft position (engine speed) sensor
  2. Damaged, chafed or corroded sensor wiring
  3. Poor connection at the sensor connector
  4. Weak sensor ground or power/5V reference problem
  5. Metal debris on the sensor or incorrect air gap
  6. Damaged reluctor wheel or tone ring
  7. Faulty PCM (rare)

How to diagnose

  1. Read all codes and freeze frame data to see when the fault occurred
  2. Inspect the sensor connector and harness for chafing, oil and corrosion
  3. Wiggle the harness and connector with the engine running while watching RPM on a scan tool
  4. Check sensor power and ground with a multimeter
  5. Test sensor resistance (magnetic type) or signal (Hall type) against specs
  6. Inspect the sensor, its mounting and gap, and the reluctor wheel
  7. Scope the signal at idle and as the engine warms up
  8. If wiring and sensor test good, evaluate the PCM

Common fixes

  • Replace the crankshaft or distributor position sensor
  • Repair the wiring harness or replace the damaged connector
  • Restore sensor power and ground circuits and clean terminals
  • Replace a damaged reluctor wheel or correct the sensor gap
  • Reflash or replace the PCM as a last resort

Questions and answers

Can I drive with a P0323 code?

Only briefly and if the engine runs smoothly. The engine could stall suddenly, so get it diagnosed soon.

What most often causes P0323?

Usually a worn crankshaft sensor or a poor connection in its connector or wiring. Checking the wiring and connector first is cheaper than replacing the sensor.

Why does the code come and go?

The fault is intermittent: a contact or sensor fails with heat or vibration. Clearing the code won't fix it, and it will return.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.