What does code P0505 mean?
P0505 means there is a fault in the idle control system. When you are off the accelerator, the computer keeps the engine at a steady speed (idle RPM). It can't hold that speed, so the car may shake, hunt up and down or stall at a stop.
Why does code P0505 appear?
- Carbon build-up on the throttle body or idle air control (IAC) valve.
- An air leak into the intake.
- The IAC valve has failed.
- The valve's wire or plug is damaged.
What can you safely check for P0505?
- Note whether the idle is too high or too low, and whether the car stalls when the AC is switched on. Tell the mechanic.
- With the engine off and cool, look under the bonnet for a rubber hose that has slipped off or cracked. Don't touch a hot engine or a running fan.
- Check the air filter: if it is very dirty or full of dust, replace it. Make sure the filter box is closed properly and its clamps are tight.
Is it safe to drive with P0505?
You can usually keep driving, but be careful: if the engine stalls, the steering and brakes become heavy. If the car stalls at signals or turns, get it fixed soon.
Safety: never remove the radiator cap on a hot engine; boiling coolant can burn you. Keep your hands away from the fan and belts while the engine runs. If you smell fuel, switch off, keep any flame or cigarette away and call a mechanic.
When should you call a mechanic?
If the code comes back, have a car mechanic (mistri) check it. Cleaning the throttle body often fixes it, but on some cars the idle has to be re-learned with a scanner after cleaning.