📖 What It Does
Regulates engine power. Open the throttle - more air comes in, the ECU adds fuel, the engine makes more power. Close it - the engine idles or decelerates.
⚙ How It Works
A pedal-position sensor sends pedal angle to the ECU. The ECU commands a small DC motor inside the throttle body to open the butterfly to a matching angle. Two redundant throttle-position sensors (TPS) confirm the actual butterfly angle. If readings disagree the ECU goes into limp mode.
⚠ Symptoms When It Fails
Symptoms include rough or surging idle, hesitation, "reduced power" warnings, P0120-P0123 codes, and stalling at stops. Carbon buildup on the butterfly is the #1 cause. Sensor wear is #2.
💰 Replacement Cost
Replacement: $300–$800. A new throttle body assembly is $200–$600. Labor is usually under an hour. Cleaning first is almost always worth trying. See throttle body cost.
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❓ Frequently Asked Questions
How often should I clean my throttle body?
Every 40,000–60,000 miles, or sooner if you notice rough idle.
Can I clean it myself?
Yes - remove the intake tube, spray throttle-body cleaner on a rag, wipe the butterfly clean. Do not blast cleaner into a closed butterfly.
Why do I need to relearn idle after cleaning?
The ECU stored a "fully closed" position based on the dirty butterfly. After cleaning, it must relearn the new zero.
What is "drive by wire"?
Electronic throttle - the pedal is electric, not cable. Almost every car since 2005 uses it.
Can a bad throttle body cause stalling?
Yes, especially at idle. Carbon buildup prevents fine idle control.
Should I use sea foam in the intake?
Only carefully and not on direct-injection engines. It can clog cats if overused.