P0505: Idle Control System Malfunction

Short answer: P0505 means “Idle Control System Malfunction”. It is a standard OBD-II code, so the basic meaning is the same on every car. Below is what it means on each of the 8 cars we cover, with a link to the full page for each car.

Standard OBD-II code Same meaning on all cars (SAE J2012).

P0505 on each car

Symptoms

1. Check engine light on
2. Engine stalls and may not idle unless throttle is depressed
3. Intermittently stalls when letting off the throttle
4. Engine may idle too high

Likely causes

1. Potential causes of an P0505 code include
2. IAC motor connector is damaged (check connector and pins for damage, and moisture)
3. One or more IAC circuits open or shorted to ground
4. One or more IAC circuits are shorted to voltage
5. IAC has failed
6. PCM has failed

What to check, in order

1. Read the code and freeze-frame data with an OBD-II scanner
2. Check the connector and wiring of the part named in the code
3. Test the part with scanner live data or a multimeter, using the values in the repair manual
4. Fix the cause, clear the code and test-drive

Causes and checks above are the general meaning. The exact test steps and values differ by car: open your car’s page.

All fault codes