Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P0506: Idle Control System RPM Lower Than Expected
- Turn the ignition switch to ON (II).
- Clear the DTC with the HDS.
- Start the engine. Hold the engine speed at 3,000 rpm without load (in P or N) until the radiator fan comes on, then let it idle.
- Check under these DATA LIST parameters with the HDS:
- ECT SENSOR 1 above 156 °F (70 °C)
- IAT SENSOR above 32 °F (0 °C)
- VSS is 0 mph (0 km/h)
- ST FUEL TRIM between 0.75-1.47
- FSS is CLOSED
- Monitor the OBD STATUS for DTC P0506 in the DTCs MENU with the HDS.
Does the screen indicate FAILED?
YES -Go to step 6.
NO -If the screen indicates PASSED, go to step 15. If the screen indicates EXECUTING, keep idling until a result comes on. If the screen indicates OUT OF CONDITION or NOT COMPLETED, go to step 4 and recheck.
- Remove the air cleaner (see AIR CLEANER REMOVAL/INSTALLATION ).
- Check for dirt, carbon, or damage in the throttle bore.
Is there dirt, carbon, or damage in the throttle bore?
YES -If there is dirt or carbon, clean the throttle body (see THROTTLE BODY CLEANING ). Also check for damage to the air cleaner element (see AIR CLEANER REMOVAL/INSTALLATION ), then go to step 9. If there is damage in the throttle bore, go to step 8.
NO -Check the A/C system and the power steering system, then go to step 17.
- Replace the throttle body (see THROTTLE BODY REMOVAL/INSTALLATION ).
- Reset the PCM with the HDS.
- Do the PCM idle learn procedure (see PCM IDLE LEARN PROCEDURE ).
- Start the engine. Hold the engine speed at 3,000 rpm without load (in P or N) until the radiator fan comes on, then let it idle.
- Check under these DATA LIST parameters with the HDS:
- ECT SENSOR 1 above 156 °F (70 °C)
- AT SENSOR above 32 °F (0 °C)
- VSS is 0 mph (0 km/h)
- ST FUEL TRIM between 0.75-1.47
- FSS is CLOSED
- Check for Pending or Confirmed DTCs or DTCs with the HDS.
Is DTC P0506 indicated?
YES -Check the A/C system and/or the power steering system, then go to step 1.
NO -Go to step 14.
- Monitor the OBD STATUS for DTC P0506 in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES -Troubleshooting is complete. If any other Pending or Confirmed DTCs were indicated in step 13, go to the indicated DTC's troubleshooting.
NO -If the HDS indicates FAILED, check the A/C system and/or the power steering system, then go to step 1. If the HDS indicates EXECUTING, keep idling until a result comes on. If the HDS indicates OUT OF CONDITION, go to step 11.
- Remove the air cleaner (see AIR CLEANER REMOVAL/INSTALLATION ).
- Check for dirt, carbon, or damage in the throttle bore.
Is there dirt, carbon, or damage in the throttle bore?
YES -If there is dirt or carbon, clean the throttle body (see THROTTLE BODY CLEANING ). Also check for damage to the air cleaner element (see AIR CLEANER REMOVAL/INSTALLATION ), then go to step 9. If there is damage in the throttle bore, go to step 8.
NO -Go to step 17.
- Recheck with different load conditions (turn on the headlights, blower motor, rear window defogger and/or A/C, change the gear position, etc.).
- Monitor the OBD STATUS for DTC P0506 in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES -Intermittent failure, the system is OK at this time.
NO -If the screen indicates FAILED, check the A/C system and/or power steering system, then go to step 1 and recheck. If the screen indicates EXECUTING, keep idling until a result comes on. If the screen indicates OUT OF CONDITION, go to step 11.
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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.