1997 Acura Integra GS-R, 4D SedanFACTORY OEM SERVICE PROCEDURE

DTC P0505: Idle Control System Malfunction

NOTE: If DTC P1508 is also set, trouble shoot that DTC before DTC P0505.
  1. Start engine and hold at 3000 RPM with no loads and transmission in Park or Neutral, until cooling fan comes on. Allow engine to idle. Using scan tool, ensure throttle position is about 10 percent with throttle fully closed and engine coolant temperature is 176-212°F (80-100°C). If throttle position and engine coolant temperature are within specification, go to next step. If throttle position or engine coolant temperature are not within specification, repair faulty sensor circuit.
  2. Using scan tool, check engine speed at idle with no loads (all accessories off). If idle speed is 700-800 RPM, problem is intermittent, system is okay at this time. If idle speed is 550 RPM or less, go to next step. On vehicles equipped with A/T, if idle speed is not 550 RPM or less, go to step 4). On vehicles equipped with M/T, if idle speed is not 550 RPM or less, go to step 5).
  3. Disconnect Idle Air Control (IAC) valve 2-pin connector. If engine speed does not drop or engine does not stall, replace IAC valve. If engine speed drops or engine stalls, adjust base idle speed. See the ADJUSTMENTS - GS-R article. If engine speed does not adjust to specification, clean throttle body and ports.
  4. On vehicles equipped with A/T, turn ignition off. Remove intake air duct from throttle body. Start engine and let idle. Place your finger over hole located next to throttle plate in throat of throttle body. If airflow is not felt, go to next step. If airflow is felt, check engine coolant level and for air in cooling system. If cooling system is okay, replace fast idle thermo valve.
  5. On all models, check for vacuum leaks. Ensure throttle valve is fully closed. Repair as necessary. If all items are okay, adjust idle speed. See the ADJUSTMENTS - GS-R article. If idle speed can not be adjusted to specification, replace IAC valve.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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