P0370

Universal

Timing Reference High Resolution Signal A Malfunction

Definition source: General OBD-II reference catalog
Definition verification: Not independently verified for display.
Time: Varies by diagnosis and vehicle | Diagnostic difficulty: Medium
Medium Severity

The engine control system has detected a problem with high-resolution timing reference signal A. This signal helps the system track engine position and timing for functions such as ignition and fuel control. A fault may cause poor running or prevent the engine from starting, but the code alone does not identify a failed part.

Report an error with this code

⚠️ Before You Begin (Safety First)

If the engine stalls, runs severely roughly, or loses power, stop driving when it is safe to do so and arrange diagnosis; an unexpected stall can create a road hazard. Avoid working near moving engine parts, and do not probe circuits unless you have the correct service information and equipment.

Common Symptoms

  • The check-engine light may be on because the control system has detected a signal malfunction.
  • The engine may crank without starting if the control system cannot use the timing reference to synchronize engine operation.
  • The engine may stall or run roughly if the signal is intermittent or unreliable.
  • Starting may be difficult or engine performance may be reduced, depending on how the vehicle responds to the signal fault.
  • There may be no noticeable symptoms if the fault is intermittent or does not significantly affect engine operation.

Common Causes

  • A damaged, loose, corroded, or poorly connected part of the timing-reference signal wiring or connector.
  • A fault in the component or system that generates high-resolution timing reference signal A.
  • Damage, contamination, or a mechanical issue affecting a trigger or reference feature, where the vehicle uses one.
  • A power, ground, or signal-circuit problem affecting the reference signal.
  • A control-system fault, considered only after the signal source and circuit have been checked.

Diagnostic Steps

  1. Note whether the engine starts, stalls, or runs roughly, and whether the issue occurs consistently or intermittently; this helps describe the fault during diagnosis.
  2. With the engine off and cool, visually inspect accessible timing-reference wiring and connectors for looseness, damage, corrosion, or contact with hot or moving parts.
  3. Check for other stored diagnostic codes with a scan tool and record them before clearing anything; related codes can help narrow the diagnosis.
  4. Consult model-, year-, and engine-specific service information before attempting electrical tests or removing components.
  5. If the code returns, the engine stalls, or the signal source is not safely accessible, have a qualified technician test the circuit and signal rather than replacing parts based on the code alone.

When to Call a Professional

A technician can review related codes and scan data, inspect the signal circuit and its connections, and test the timing-reference signal with suitable equipment. The signal source, wiring, and control system should be evaluated before replacing parts. Testing procedures and expected signals depend on the vehicle's model, year, and engine.

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Commonly Asked Questions

Does P0370 prove that a timing-reference sensor has failed?

No. The code identifies a detected malfunction in high-resolution timing reference signal A. Wiring, connections, the signal-generating system, or another control-system issue may also be involved.

Can I keep driving with P0370?

That depends on how the engine behaves. If it stalls, runs severely roughly, or loses power, stop driving when safe and arrange diagnosis. A vehicle with no noticeable symptoms still needs checking because the fault may return.

Why might the vehicle have P0370 but no noticeable symptoms?

The signal problem may be intermittent or may not yet be affecting engine operation enough to be noticeable. A scan-tool check and circuit diagnosis can help determine whether the condition is current or intermittent.

What should be checked before replacing a part?

Check related codes, accessible wiring and connectors, and the timing-reference signal itself using vehicle-specific service information. The correct test depends on the model, year, and engine.

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.