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DTC codes / P03xx · Ignition system and misfire / P0323

P0323Ignition/Distributor Engine Speed Input Circuit Intermittent

P0323 indicates that the powertrain control module (PCM) has detected an intermittent fault in the ignition or distributor engine speed input circuit, which provides the crankshaft position or engine speed signal. The PCM sets this code when the signal from the distributor or ignition module drops out or becomes erratic for brief periods, even though the engine may continue running.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaIgnition system and misfire

Symptoms you may notice

  • The check engine light (malfunction indicator lamp) illuminates, often with no other noticeable symptoms.
  • The engine may hesitate or stumble intermittently, especially under acceleration or load.
  • Intermittent stalling or a no-start condition that comes and goes.
  • A rough idle or misfire that appears randomly.
  • The tachometer needle may jump or drop erratically if the signal is used for the gauge.

Common causes, most likely first

  1. Faulty or failing crankshaft position sensor or distributor pickup coil.
  2. Damaged or corroded wiring in the engine speed input circuit, including chafed insulation or broken strands.
  3. Loose or corroded electrical connectors at the sensor, ignition module, or PCM.
  4. A failing ignition control module or distributor assembly that intermittently loses the signal.
  5. Excessive play or damage in the distributor drive gear or timing chain/belt causing an erratic signal.
  6. Electrical interference from aftermarket accessories or poor grounding.
  7. A PCM internal fault, though this is rare and should be considered only after all other possibilities are ruled out.

How to diagnose and fix it

  1. Inspect the wiring harness and connectors for the crankshaft position sensor or distributor pickup, looking for chafing, corrosion, or loose pins.
  2. Perform a wiggle test on the harness and connectors while the engine is running to see if the code sets or the engine stumbles.
  3. Check the resistance and signal output of the crankshaft position sensor or distributor pickup coil with a multimeter or oscilloscope, comparing to manufacturer specifications.
  4. Verify the distributor drive gear and timing components for excessive play or damage that could cause an erratic signal.
  5. Inspect and clean all ground connections related to the ignition system and PCM.
  6. If the sensor and wiring are good, test the ignition control module and replace if faulty.
  7. Clear the code and perform a road test to confirm the repair, monitoring live data for the engine speed signal.

Intermittent Signal Faults Are Rarely the Sensor

  • A loose or corroded connector pin is a more common cause of an intermittent engine speed signal than a failed sensor, so always perform a thorough visual and wiggle test before replacing parts.
  • The code can be set by a momentary dropout that lasts only milliseconds, which may not be felt by the driver and may not appear during a brief test drive.
  • Aftermarket alarm systems or remote starters that tap into ignition wiring can introduce electrical noise that mimics a failing sensor.
  • On vehicles with a distributor, a worn distributor shaft bushing can cause the pickup coil air gap to vary, producing an intermittent signal without any visible wiring damage.
  • A failing ignition coil or spark plug wires can create electrical interference that disrupts the engine speed signal, so a full ignition system check is warranted.

Can I keep driving with P0323?

If the engine runs smoothly and the only symptom is the warning light, you can drive cautiously to a repair shop, but avoid heavy acceleration or long trips. If the engine hesitates, stalls, or misfires, stop driving and have the vehicle towed to prevent safety risks and further damage.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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