Air intake
Throttle Body
The throttle body controls how much air enters the engine through the accelerator.
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Air intake flow
Interactive — tap a partTap a part to see how it fits in the system.
What it does
- Regulates intake airflow via the butterfly
- Houses the idle control and throttle position sensors
- Modern cars use electronic (drive-by-wire) throttle
When it fails
- Rough or hunting idle
- Stalling when slowing
- Poor throttle response
- Carbon deposits visible on the butterfly
How to diagnose
- Clean the butterfly and bore with throttle cleaner
- Read TPS sweep live
- Check idle control operation
- Re-learn the idle on some cars after cleaning
Maintenance
- Clean every 30,000–50,000 km
- Use the correct cleaner, not brake cleaner
- Re-learn idle per the manual after cleaning
Use the diagnosis order. When a part fails, confirm each hypothesis with measurements before replacing anything — codes and symptoms overlap.
Related part
Mass Airflow Sensor
The MAF sensor measures how much air the engine is breathing so the ECU can meter fuel.