Idle and throttle

P0505 Idle speed won't stay steady

By: Diagno editorial team · Updated: 2026-10-15

P0505 means: Idle speed won't stay steady. The engine computer can't hold the idle speed steady. OK to drive, but have it checked soon. The repair usually costs about €30–300 in Estonia. The most common cause: dirty throttle body. Other possible causes: air leak, idle control valve has failed.

Is it safe to drive?OK to driveOK to drive, but have it checked soon.

Typical repair cost€30–300parts and labour in Estonia

What it means

The engine computer can't hold the idle speed steady. The idle is too low, too high or hunting.

What could be wrong

1Dirty throttle body
2Air leak
3Idle control valve has failed
4Throttle needs to be re-learned

What you can check yourself

Listen for a hissing sound. A dirty throttle body is a very common cause. You can do the simpler checks yourself.

How we fix it

We clean the throttle body and re-learn it
We check for air leaks
We replace the idle control valve or throttle body

Standard SAE description: Idle Control System Malfunction

Want a definite answer?

Bring the car to our workshop in Estonia for diagnostics. We read the fault codes, test the sensors and tell you what is wrong. Repair price depends on the work involved, generally €45 per hour.

Book a diagnostic check

Questions

What does fault code P0505 mean?

Idle speed won't stay steady. The engine computer can't hold the idle speed steady. The idle is too low, too high or hunting.

Can I drive with code P0505?

OK to drive, but have it checked soon.

How much does it cost to fix P0505?

Roughly €30–300 in Estonia. The price depends on exactly what has failed and on the car.

How is P0505 fixed?

We clean the throttle body and re-learn it. We check for air leaks. We replace the idle control valve or throttle body.

Based on AI combined with our hands-on workshop experience and knowledge. This information is general and prices are approximate (Estonian workshop rates). The same code can mean different things on different cars. Only an inspection of the car gives a definite answer.