P0320: Ignition/Distributor Engine Speed Input Circuit Malfunction
May cause engine hesitation, stalling, difficulty starting, and misfires; potentially inhibit engine start or operation depending on severity.
Overview
P0320 indicates a malfunction in the ignition/distributor engine speed input circuit, typically involving the crankshaft position sensor or related wiring and signaling circuits.
Common Symptoms
- Check Engine Light (CEL) illuminated
- Engine hesitates, stumbles, or misfires
- Engine cranks but does not start
- Reduced power or acceleration issues
Most Common Causes
Primary cause of signal disruption to the PCM leading to code P0320.
Wiring harness issues frequently interrupt sensor communication.
Depending on engine design, related input sensors can trigger P0320.
Electrical faults in supply or ground lines can mimic sensor failure.
Less common but possible if all sensor and wiring tests check normal.
Diagnostic Steps
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Verify P0320 code with OBD-II scanner and check for additional codes.Expected: P0320 present; note if other related codes present (e.g., P0335, P0340).Interpretation: Confirm baseline before beginning circuit tests.
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Visually inspect crankshaft and camshaft position sensor wiring and connectors.Expected: Clean, undamaged connectors; no frayed or exposed wiring.Interpretation: Damage or corrosion indicates wiring repair required.
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Test sensor power supply and ground at sensor harness with a multimeter.Expected: Proper reference voltage (often 5V) and good ground.Interpretation: Incorrect readings indicate supply/ground circuit faults.
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Measure sensor output signal while cranking (e.g., AC voltage for magnetic pickup).Expected: Signal within manufacturer spec.Interpretation: Absent or erratic signal suggests sensor or tone wheel issues.
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If sensors and wiring test good, evaluate ECM/PCM input circuits.Expected: Proper diagnostic interface readings.Interpretation: Persistent faults with no wiring/sensor errors raise ECM/PCM concerns.
Repair Solutions
Most common and effective repair when sensor fails.
Cost varies with extent of wiring harness repair needed.
Applicable on engines where this sensor contributes to engine speed input.
Considered only after all sensor and wiring diagnostics are completed.
Common Misdiagnoses
Avoid these common diagnostic mistakes:
- Replacing crankshaft position sensor without checking wiring/connectors first
- Faulty camshaft position sensor incorrectly blamed for P0320
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