What Does P0371 Mean?
The ECM is detecting too many pulses from the timing reference high resolution signal A. The pulse count per engine revolution exceeds the expected number for the reluctor wheel configuration, indicating the ECM is seeing extra or spurious pulses. This causes inaccurate crankshaft position calculations, leading to incorrect ignition timing, potential misfires, and compromised misfire detection capability.
Common Causes
30%
Damaged or cracked reluctor wheel with extra raised features or debris creating additional pulses
25%
Electromagnetic interference on the timing reference signal wire from nearby ignition or charging system components
20%
Failing timing reference sensor producing noise and false trigger pulses
15%
Excessive sensor-to-reluctor proximity (air gap too small) causing the sensor to pick up minor surface irregularities as additional pulses
10%
Metallic debris adhering to the magnetic sensor tip or reluctor wheel surface creating false trigger points
Diagnostic Steps
1
Capture the timing reference signal on an oscilloscope and count the pulses per engine revolution — compare to the expected number for the reluctor wheel (e.g., 58 pulses for a 60-2 wheel). Extra pulses will be visible as irregular additions to the pattern.
2
Inspect the reluctor wheel for physical damage, cracks, debris accumulation, or welding spatter — any raised material on the wheel surface will generate extra pulses.
3
Remove the timing reference sensor and clean the magnetic tip of any metallic debris — reinstall and verify the air gap is within specification (not too close).
4
Check the timing reference signal wiring for proper routing and shielding — ensure the harness is not routed alongside ignition coil wires, alternator output cables, or other high-current/high-voltage conductors.
5
If the signal wire has a shield, verify the shield is properly grounded at one end only — an ungrounded or double-grounded shield can allow EMI to corrupt the signal.
Estimated Repair Cost
$150 - $800
Parts + labor, varies by vehicle and location
The ECM is detecting too many pulses from the timing reference high resolution signal A. The pulse count per engine revolution exceeds the expected number for the reluctor wheel configuration, indicating the ECM is seeing extra or spurious pulses. This causes inaccurate crankshaft position calculati...
The most common cause of P0371 (Timing Reference High Resolution Signal A Too Many Pulses) is: Damaged or cracked reluctor wheel with extra raised features or debris creating additional pulses
Typical repair costs for P0371 range from $150 to $800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Drive cautiously. Extra timing pulses cause the ECM to miscalculate crankshaft position, which can result in incorrect ignition timing and misfires. The engine may run rough but is unlikely to stall suddenly. Avoid high-RPM operation where timing accuracy is most critical for engine safety.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0371 to identify the root cause.
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Quick Info
Category
Powertrain
System
Ignition System
Difficulty
Type
Generic (SAE)
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