Engine Speed Input Circuit Intermittent
Your engine's computer is having trouble reading the crankshaft position sensor signal consistently—like a radio that keeps cutting out. This causes the ECU to lose track of engine speed intermittently, triggering the fault code.
The ECM monitors the crankshaft position (CKP) sensor signal to determine engine RPM and ignition timing. It expects a continuous, clean signal with consistent frequency based on engine speed. Intermittent dropouts or noise in this signal trigger P0730.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| CKP Signal Frequency | Continuous pulses matching engine RPM | Signal dropout or erratic pulses lasting >100ms |
| Signal Voltage Stability | 0-5V with clean rising/falling edges | Noise, dropout, or missing edges detected |
Code P0730 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P0730 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.