Ignition Spare
The engine control computer detected an issue with the ignition timing spare circuit, similar to a backup ignition system not responding when needed. This typically means a wiring problem or sensor failure in the secondary ignition control pathway.
The ECU monitors the spare ignition control circuit for proper voltage and signal continuity. It expects consistent feedback from the secondary ignition pathway within defined voltage thresholds during engine operation. A fault occurs when the signal deviates outside normal operating parameters or fails to respond.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Spare Ignition Circuit Voltage | 4.5-5.5V | Below 3.5V or above 6.5V |
| Signal Response Time | Within spec milliseconds | Delayed or no response detected |
Code P1372 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, P1372 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.