Ignition/Distributor Engine Speed Input Circuit No Signal
The Engine Control Module (ECM) uses the engine speed input circuit, typically the crankshaft position sensor, to determine engine RPM and ignition timing. Code P0322 is set when the ECM detects a complete loss of signal from this circuit while the engine is cranking or running.
This is a high-priority issue because a missing engine speed signal will typically cause the engine to stall unexpectedly or fail to start, leaving you stranded.
Common symptoms
- Engine cranks but will not start
- Engine stalls unexpectedly while driving
- Illuminated Check Engine Light
- Rough idling or engine hesitation
- Tachometer drops to zero while the engine is running
Likely causes
- Faulty engine speed sensor (crankshaft position sensor)
- Corroded, loose, or damaged sensor electrical connector
- Broken or shorted wiring in the sensor circuit
- Faulty distributor pickup coil (on older distributor-equipped vehicles)
- Metal debris on the magnetic sensor tip
- Failed Engine Control Module (ECM)
What to check before replacing parts
Visually inspect the engine speed sensor wiring and connector.
Look for: Look for broken wires, melted insulation, corrosion, or oil contamination at the sensor connector that could interrupt the signal.
Remove and inspect the engine speed sensor for physical interference.
Look for: Look for physical damage or a buildup of metal shavings on the magnetic tip of the sensor that could block the reluctor wheel signal.
Test the sensor's internal resistance using a digital multimeter.
Look for: Look for an open circuit (infinite resistance) or resistance values that fall outside the manufacturer's specified range.
Check for proper reference voltage and ground at the sensor connector.
Look for: With the key on and engine off, look for a steady reference voltage (usually 5V or 12V depending on the vehicle) and a solid ground.
Monitor the sensor output signal using an oscilloscope or advanced scan tool.
Look for: Look for a missing, erratic, or flat-lined waveform (square or sine wave) while cranking the engine, indicating the sensor is not generating a signal.
This page explains the generic P0322 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
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