P0371
UniversalTiming Reference High Resolution Signal A Too Many Pulses
The engine control system has detected more pulses than expected on timing reference high-resolution signal A. This signal helps the system track engine timing. An irregular signal can affect starting, engine operation, or timing control, but the code alone does not prove that a particular sensor or other part has failed. Exact applicability and diagnostic procedures depend on the vehicle's model, year, and engine.
⚠️ Before You Begin (Safety First)
If the engine stalls, runs very roughly, or becomes difficult to control, pull over safely and stop driving; arrange diagnosis or towing. If the vehicle runs normally, avoid hard driving and have the fault checked soon, since an intermittent timing signal problem could worsen.
Common Symptoms
- There may be no noticeable symptoms if the condition is intermittent or does not disrupt engine operation.
- Hard starting or failure to start may occur if the engine control system cannot reliably interpret the timing signal.
- Rough running, hesitation, or misfiring may occur if an irregular signal affects engine timing control.
- The engine may stall if the timing reference signal becomes unreliable while driving.
Common Causes
- Electrical noise or an intermittent connection may create extra signal transitions.
- Damaged, chafed, or poorly connected wiring may distort the timing reference signal.
- A fault in the signal-generating sensor or its circuit may produce an irregular pulse pattern.
- Damage, contamination, or another issue at the timing signal target may affect the signal pattern, if this vehicle uses such a target.
- An installation, compatibility, or adjustment issue may affect the signal where applicable.
- A control-module input or processing fault is possible, but should be considered only after other causes are checked.
Diagnostic Steps
- Note whether the engine has hard-starting, rough-running, hesitation, or stalling symptoms, and avoid driving if it stalls or becomes unsafe.
- With the engine off, visually inspect accessible wiring and connectors for looseness, corrosion, or visible damage; do not disconnect components while the engine is running.
- Check for other stored diagnostic codes with a scan tool and record them before clearing anything, since related codes may help narrow the cause.
- Use model-, year-, and engine-specific service information to identify the correct signal circuit and safe inspection points; do not guess at component location or adjustment.
- If visual checks do not reveal a clear issue, have a qualified technician evaluate the signal waveform and circuit rather than replacing parts based on this code alone.
When to Call a Professional
A technician can review related codes and scan data, inspect the signal circuit and connections, and use an oscilloscope or other suitable equipment to assess signal A for extra transitions or electrical interference. The signal source and any timing target should be checked using vehicle-specific service information before replacing parts. Consider a control-module fault only after the signal source, wiring, and connections have been evaluated.
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Commonly Asked Questions
Does P0371 mean the timing sensor must be replaced?
No. It indicates that the system detected too many pulses on timing reference high-resolution signal A. Wiring, electrical interference, the signal source, or other issues can also cause an irregular pulse pattern.
Can the vehicle be driven with this code?
That depends on how the engine is behaving. If it stalls, runs very roughly, or is difficult to control, stop driving and arrange service. If it appears to run normally, have it checked soon because the issue could become intermittent or worsen.
What does the timing reference signal do?
It provides the engine control system with timing information used to coordinate engine operation. The precise signal source and system design vary by vehicle.
How is an extra-pulse condition diagnosed?
A technician can inspect the circuit and connections, review scan data and related codes, and examine the signal waveform with suitable diagnostic equipment. Vehicle-specific service information is needed to interpret the results.
Browse Available Code Guides
Previous and next available guides in database record order, across makes. Adjacent entries may share a code number and do not necessarily describe related faults.