Timing Reference High Resolution Signal A Malfunction
Your engine's timing sensor (like a heartbeat monitor for spark timing) isn't sending a clear signal to the computer. Think of it like a radio station that's too weak or static-filled for the receiver to understand properly.
The ECU monitors the crankshaft position sensor (CKP) or camshaft position sensor (CMP) signal quality and frequency to determine precise ignition timing. The sensor must provide a clean, consistent high-resolution signal within specific voltage and frequency windows. If the signal is weak, noisy, or intermittent, the ECU cannot calculate proper spark advance.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Signal Voltage Amplitude | 0.2-5V peak-to-peak (sensor dependent) | Below 0.2V or erratic signal dropout |
| Signal Frequency/Consistency | Stable, repeatable pulse pattern matching engine RPM | Dropout, noise, or missing teeth detection |
Code P0371 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, P0371 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.