P0291

Universal

Cylinder 11 Injector Circuit Low

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 low electrical condition in the injector circuit for cylinder 11. The injector meters fuel into its cylinder, and the control system monitors its electrical circuit to check that it can operate as intended. This code points to an electrical circuit condition, not proof that the injector itself has failed. Depending on the vehicle and fault, engine performance or emissions may be affected.

Report an error with this code

⚠️ Before You Begin (Safety First)

If the engine runs very roughly, loses significant power, or the check-engine light flashes, stop driving when safe and arrange diagnosis; continued operation with a severe misfire can damage the vehicle. If the vehicle runs normally, avoid hard acceleration and have the fault checked promptly. Cylinder numbering and applicability depend on the engine.

Common Symptoms

  • The check-engine light may be on, with or without noticeable drivability changes.
  • A rough idle or engine misfire may occur if cylinder 11 receives incorrect or insufficient fuel.
  • Reduced power or uneven acceleration may occur if the affected cylinder is not contributing normally.
  • Fuel economy or emissions may worsen if the engine runs unevenly.
  • There may be no noticeable symptoms, especially if the fault is intermittent or the control system compensates.

Common Causes

  • Damaged wiring or a poor connection in the cylinder 11 injector circuit may disrupt its electrical signal.
  • Corrosion, looseness, or damage at the injector connector may cause an abnormal circuit reading.
  • An electrical fault within the injector may affect the circuit.
  • A fault in the injector circuit's power supply, control wiring, or engine-control driver may produce a low circuit condition.

Diagnostic Steps

  1. Check the vehicle's model, year, and engine service information to confirm that cylinder 11 applies and to identify it correctly.
  2. Record the code and any available freeze-frame information before clearing codes; this can help show when the condition occurred.
  3. With the engine off and cool, visually inspect the accessible injector wiring and connector for obvious damage, looseness, or corrosion. Do not pull on wires or disconnect components while the engine is running.
  4. If the wiring and connector look intact, avoid replacing the injector based on the code alone. Arrange circuit testing with the correct wiring diagram and vehicle-specific procedure.

When to Call a Professional

Confirm that the vehicle and engine use a cylinder 11 injector circuit, then review scan data and freeze-frame information. Using the correct wiring diagram, a technician can inspect the injector connector and harness, test the circuit and injector electrically, and check the control-system driver. Results should be interpreted using vehicle-specific procedures before replacing parts.

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Commonly Asked Questions

Does P0291 prove that the cylinder 11 injector needs replacement?

No. It identifies a low electrical condition in the injector circuit. Wiring, connections, the injector, its power or control path, and the engine-control driver may need to be checked before deciding what to repair.

Does this code mean cylinder 11 is getting low fuel pressure?

Not by itself. The definition describes an electrical injector-circuit condition, not a measured fuel-pressure problem.

Can I drive with P0291?

That depends on how the engine is running. Avoid continued driving if the check-engine light flashes, the engine misfires severely, or power drops significantly. If symptoms are mild or absent, arrange diagnosis promptly and avoid hard acceleration.

How can I find cylinder 11?

Cylinder numbering depends on the engine design. Use service information for the exact model, year, and engine rather than assuming a location.

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