P0337

Universal

Crankshaft Position Sensor A Circuit Low Input

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 crankshaft position sensor provides information the engine computer uses to track crankshaft rotation and position. P0337 means the computer detected a low input in the Sensor A circuit. This can interfere with engine timing and may cause starting or running problems, but the code alone does not prove the sensor needs replacement.

Report an error with this code

⚠️ Before You Begin (Safety First)

If the engine stalls, is difficult to keep running, or cannot be restarted reliably, avoid driving in traffic and arrange safe assistance. Stop driving if the vehicle cannot be controlled safely. Exact diagnosis and procedures depend on the vehicle’s model, year, and engine.

Common Symptoms

  • The engine may crank without starting if the computer cannot reliably determine crankshaft position.
  • The engine may stall or run unevenly if the signal becomes unreliable while running.
  • Starting may be intermittent, particularly if a connection or wire makes inconsistent contact.
  • The check-engine light may be on, and the code may be stored without noticeable symptoms.

Common Causes

  • A crankshaft position sensor may produce an unexpectedly low or unreliable signal.
  • A loose, damaged, corroded, or contaminated sensor connector can disrupt the circuit.
  • Damaged wiring, a poor electrical connection, or a short in the circuit may lower the input.
  • A problem with the signal-generating components or their alignment may affect the sensor output.
  • A fault in the engine computer or its circuit connections is possible but should be considered only after appropriate checks.

Diagnostic Steps

  1. Confirm the code with a scan tool and note any other codes; related codes can help guide diagnosis.
  2. With the engine off and cool, visually inspect accessible sensor wiring and connectors for looseness, corrosion, damage, or contamination. Do not pull on wires or work near moving parts.
  3. Check whether the code returns after clearing it and following the vehicle’s normal operating conditions. A returning code may help distinguish an active problem from an intermittent or stored one.
  4. If you have a scan tool, observe engine-speed data while cranking and compare it with vehicle-specific service information. Missing or implausible data calls for further circuit diagnosis, not automatic sensor replacement.
  5. Use the correct service information for any electrical tests. If testing requires access near moving parts, specialized signal equipment, or procedures you are not equipped to perform, have a qualified technician continue.

When to Call a Professional

Confirm the code and check for related codes and scan data, including whether engine speed is detected during cranking. Inspect the sensor circuit and connector, then test power, ground, wiring continuity, and signal using vehicle-specific service information. A scope or other suitable test equipment can help distinguish a sensor signal problem from wiring or computer-side issues.

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Commonly Asked Questions

Does P0337 prove the crankshaft position sensor is faulty?

No. It reports a low input in the Crankshaft Position Sensor A circuit. The sensor, connector, wiring, signal-generating components, or computer-side circuitry may need investigation.

Can the vehicle be driven with P0337?

It depends on how the engine behaves. If it stalls, runs unpredictably, or may not restart, avoid driving it in traffic and arrange safe assistance.

Why might the engine crank but not start?

The engine computer uses crankshaft position information to coordinate engine operation. If the circuit signal is missing or unreliable, the computer may not have the information it needs for starting.

What distinguishes a sensor problem from a wiring problem?

Inspection and circuit testing can check the connector, wiring, power, ground, and signal. Scan data or signal testing with suitable equipment can help narrow down the cause; procedures depend on the vehicle.

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