P0322 - Ignition/Distributor Engine Speed Input Circuit No Signal
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System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
P0322 is a generic diagnostic trouble code (DTC) indicating that the Engine Control Unit (ECU) has detected a lack of signal from the engine speed sensor (Crankshaft Position Sensor or Ignition/Distributor speed sensor). The ECU relies on this pulse to determine engine RPM and crankshaft position for timing fuel injection and ignition sparks. If the signal is absent or erratic (intermittent skip) during cranking or engine operation, the ECU cannot maintain engine internal timing synchronization, leading to an immediate shutdown or failure to start.
Possible Causes
Faulty Crankshaft Position (CKP) sensor
Damaged wiring harness or corroded connector at the sensor
Faulty distributor ignition engine speed sensor (on older models)
Damaged reluctor ring (trigger wheel) on the crankshaft or internal ECU failure
Symptoms
Recommended Solution
- STEP 1: Inspect the crankshaft sensor connector for oil intrusion, corrosion, or backed-out pins. Check the wiring harness for signs of fraying.
- STEP 2: Measure the sensor resistance (Ohm). Normal values typically range from 500-1500 Ohms (check specific service manual). An 'Open' reading indicates a dead sensor.
- STEP 3: Verify reference voltage (usually 5V or 12V depending on sensor type) and ground integrity at the sensor harness.
- STEP 4: Use an oscilloscope to monitor the waveform while cranking. Look for consistent pulse patterns (Square wave for Hall effect, Sine wave for Inductive).
- STEP 5: Replace the Crankshaft Position Sensor if tests fail. Clear codes and perform a road test.
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
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