When does a throttle body need to be serviced

The throttle body service is not a part of a scheduled maintenance, but for some problems, it may offer a simple solution. First, what is a throttle body and why does it need to be serviced? A throttle body is an electronic device that operates the throttle valve. All modern cars have a drive-by-wire system where pressing the accelerator pedal sends the signal to the computer that in turn activates the throttle valve.

Throttle body

Throttle body

The throttle valve controls engine RPMs by regulating the air flow. A small electric motor inside the throttle body opens and closes the throttle valve. Besides responding to the gas pedal, the throttle body has one more important function: in most cars, it maintains the engine idle speed. When you are waiting for the green light at the intersection, your engine runs at a slow speed, typically between 550 and 700 RPMs. To maintain the stable idle speed, the throttle body keeps the throttle valve open at a small angle, constantly adjusting it depending on the conditions. Over time, carbon deposits accumulate on the throttle valve and throttle body, preventing it from operating correctly. In some cars, this may cause the throttle valve to stick, resulting in low or unstable idle speed or stalling. In addition, the Check Engine light may come on. If the diagnosis reveals a dirty throttle body as a potential cause of the problem, your mechanic may suggest the throttle body service. Usually it involves cleaning the throttle body with a special cleaning solution and removing carbon deposits from the throttle valve. In some cars, the idle speed must be re-learned after the service was done.

Dirty throttle body

Dirty throttle body removed for cleaning

The throttle body service is not very expensive, ranging from $60 to $180 depending on the complexity. At what mileage should this service be done? There is no specific mileage requirements and some cars may never need this service. Usually the throttle body gets dirty at higher mileage (after 50K-80K miles), mostly in cars that are often driven in  stop-and-go city traffic or when oil changes are not done regularly. Is it worth to do this service if your car is regularly maintained and your engine runs smoothly? We would not recommend it unless the throttle body is really dirty and your mechanic thinks that it may cause problems. On the other hand, if your car stalls or runs unstable at idle, the throttle body is the common suspect and your mechanic would usually check its condition as a part of the diagnostic process. Is it easy to check the throttle body condition? In most cars, it’s not very difficult. The throttle body is installed at the intake manifold and to check its condition your mechanic may have to remove the intake boot.  Is it possible to clean the throttle body as a DIY project? Some manufacturers require a very specific procedure to clean the throttle body. If not done properly, the throttle body might get damaged and it’s an expensive part to replace. For this reason, we would strongly suggest to consult the manufacturer’s service manual or have this service done by a qualified technician.

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How often does your car need a tune-up »
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