What Does P0372 Mean?
The ECM is detecting too few pulses from the timing reference high resolution signal A. The pulse count per engine revolution is less than expected for the reluctor wheel configuration, meaning pulses are being lost or dropped. This results in gaps in the ECM's crankshaft position data, causing timing inaccuracies, misfire detection errors, and potentially rough engine operation.
Common Causes
30%
Damaged reluctor wheel with missing, broken, or worn teeth causing signal dropouts
25%
Excessive air gap between timing reference sensor and reluctor wheel causing weak pulses that fall below the ECM detection threshold
20%
Failing timing reference sensor with weak magnetic field or degraded output not generating sufficient pulse amplitude on all teeth
15%
High resistance or intermittent open in the timing reference signal circuit attenuating some pulses below detection threshold
10%
Debris or contamination filling the gaps between reluctor wheel teeth, reducing the signal contrast between tooth and slot
Diagnostic Steps
1
Capture the timing reference signal on an oscilloscope and look for missing pulses, low-amplitude pulses, or irregular spacing — this will identify whether the issue is specific teeth on the reluctor wheel or a general signal weakness.
2
Inspect the reluctor wheel through the sensor bore or transmission inspection cover for missing, broken, or severely worn teeth — use a borescope for better visibility.
3
Check the timing reference sensor air gap — if adjustable, verify it meets the manufacturer specification; on non-adjustable sensors, ensure the mounting bore is not elongated or allowing the sensor to sit too far from the wheel.
4
Measure the timing reference sensor output amplitude at idle — a healthy sensor should produce uniform pulse amplitudes. Significantly lower amplitude on some pulses indicates damaged wheel teeth, while uniformly low amplitude suggests a weak sensor or excessive gap.
5
Clean the reluctor wheel surface if accessible — packed debris, oil sludge, or rust between teeth reduces the magnetic flux variation that generates the signal pulses.
Estimated Repair Cost
$150 - $800
Parts + labor, varies by vehicle and location
The ECM is detecting too few pulses from the timing reference high resolution signal A. The pulse count per engine revolution is less than expected for the reluctor wheel configuration, meaning pulses are being lost or dropped. This results in gaps in the ECM's crankshaft position data, causing timi...
The most common cause of P0372 (Timing Reference High Resolution Signal A Too Many Pulses) is: Damaged reluctor wheel with missing, broken, or worn teeth causing signal dropouts
Typical repair costs for P0372 range from $150 to $800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Drive carefully. Missing timing pulses reduce the ECM's ability to accurately control ignition timing and detect misfires. The engine may run rough, especially at higher RPMs where the missing pulses cause more significant timing errors. Avoid high-load, high-RPM driving until the issue is resolved.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0372 to identify the root cause.
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Quick Info
Category
Powertrain
System
Ignition System
Difficulty
Type
Generic (SAE)
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