P1505 Code failures by brands


Description of DTC code P1505

The Idle Speed Control Valve (ISCA) is located on the intake manifold. Its function is to regulate the flow of intake air that is bypassed near the throttle plate to maintain a constant engine speed when the throttle valve is closed. The ISCA valve maintains the idle speed according to engine conditions and loads. Besides, it provides additional air during start-up.

The idle speed control valve design is composed of a closing coil, an opening coil, and a permanent magnet. The Engine Control Module (ECM) controls the two-coil based on information from various sensors. To do this, it grounds its control circuits, and taking into account the ECM control signals, the valve rotor turns for through-air flow control to the engine.

The P1505 OBDII fault code is set because after one minute of engine operation, the ECM detected that the idle speed control reached its air setting limit during the self-test, and the actuator signal is excessively below the allowable levels.

Symptoms of fault code P1505

  • Check Engine light on.
  • Irregular motor operation.
  • The engine stops unexpectedly.

Causes of OBD2 P1505

The reasons for storing the P1505 OBD2 diagnostic code are:

  • The idle speed control valve harness may have damage to the wiring or its connectors.
  • The electrical connections of the ISCA valve may be faulty, resulting in a short circuit.
  • The Idle Speed Control Actuator may be in bad condition.

Possible solutions of the DTC code P1505

The steps to follow to troubleshoot DTC P1505 OBDII are as follows:

  • To begin the diagnosis, we recommend that you consult the Technical Service Bulletins.
  • Check there is no damage to the wires or connectors corresponding to the idle speed control valve circuit. Any condition such as burns, corrosion, or wear will require repairs or replacement.
  • Measure the ISCA valve circuit voltages and check that they are within the range specified by the manufacturer in the service manual. An out-of-range voltage is due to a short, open circuit or poor connection. Repair if necessary.
  • Determine the good condition of the idle speed control valve, taking into account the diagnostic steps set by the manufacturer. Replace it in case of damage.

Codes related to P1505

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