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.

2006 Mazda MX-5 Miata BaseFACTORY OEM SERVICE PROCEDURE

DTC P0505: Notes

DETECTION CONDITION AND POSSIBLE CAUSE (DTC P0505)

DTC P0505	Idle speed control system problem
DETECTION CONDITION	The PCM cannot control idle speed toward target idle speed while KOER self test.
POSSIBLE CAUSE	Drive-by-wire control system malfunction Air cleaner element clogged Air intake passage clogged A/C relay control circuit malfunction Generator control circuit malfunction Low engine compression (Over capacity of blow-by gas) PCM malfunction

Factory Service Tools

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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.