An electronic throttle body is basically a cylinder that intake air flows through, with a rotating plate in the middle that can open or close to allow or block airflow. It’s a part of the engine’s air intake system, sitting where the carburetor sat on older design engines. The first throttle bodies were similar in design – the throttle plate was opened by a cable from the gas pedal, and they incorporated one or two fuel injectors. On most modern vehicles the fuel injection has moved to a separate injector at each cylinder farther down on the intake, and on the throttle, the plate is operated by an electric motor rather than a cable.
Which leaves a very simple electronic throttle body, which is a cylinder with a throttle plate to control airflow, with an electronic module on the side housing the motor and sensors. Some throttle bodies incorporate separate idle control mechanisms, but most of the time that is handled by minute running adjustments of the throttle plate opening itself now. Some throttle bodies also have coolant lines that circulate hot coolant around the plate, warming it and preventing icing in winter.
The only service, maintenance, or repair that is typically possible is to clean the throttle plate. Manufacturers normally recommend this to be done about every 15,000 miles, as residues build up and can interfere with the full closing of the plate, or with its smooth operation. Cleaning the throttle body can be done with an intake system cleaner, which sprays a solvent into the air intake. What still works better though is to take a little bit of solvent on a damp rag and wipe it clean, the same as has been done for ages. Some throttle bodies are right on top and can be pulled, inspected, and cleaned easily. On others, it’s more practical to clean them in place.
If the throttle body is cleaned using an injected solvent, the cost varies between $50 and $150. If the throttle body is cleaned manually the cost is usually half an hour of labor, or about $50.
Costs of Throttle Body Replacement
The average cost to replace a throttle body is about $350.
For some more specific estimates on throttle body replacement on common vehicles, using $100 an hour as a labor rate:
For a 2002 Dodge Ram 1500 with a 4.7 liter engine, the labor time to replace a throttle body is .6 of an hour. A factory throttle body costs about $270, and there’s no aftermarket source currently. That makes the job about $330 using OE parts.
For a 2008 Kia Optima with a 2.4 liter engine, the labor time to replace the throttle body is .6 of an hour. A factory throttle body costs about $410, and a Spectra part costs about $220. This makes the job about $470 using OE parts, or about $280 using aftermarket parts.
For a 2004 Toyota Corolla with a 1.8 liter engine, the labor time to replace the throttle body is 1.5 hours. A factory parts costs about $1293, and a Beck/Arnley throttle body costs about $290. That makes the job about $1443 using OE parts, or about $440 using aftermarket parts.
In all cases there may be a standard hour of diagnostic labor added.
Indications of Throttle Body Problems
In most cases the main indication is an engine light. The throttle body is a highly monitored component; it has sensors built in that inform the PCM of the throttle plate position; as with the accelerator pedal, there are two sensors for redundancy. This position is them compared to the airflow entering the intake, the vacuum in the intake, and the O2 sensor’s reading of the results of combustion. If the numbers don’t add up, the PCM can throw a trouble code for various things. Sometimes if the manifold vacuum reading is off it will assume a vacuum leak, but that can also be a throttle plate that’s not closing properly. More often a fault in the throttle position sensors will cause a code.
One of the warning lights on the cluster is a red lightning bolt that indicates the electronic throttle. In the same way that a red light shaped like a battery indicates an alternator problem, the red lightning bolt doesn’t make a lot of sense, but that being lit indicates that there is a throttle body problem. In many cases a vehicle will go into “limp mode’, which reduces engine power and speed, if a problem is sensed. Sometimes a vehicle can be shut off and restarted, which puts it back into normal operating mode as long as a problem doesn’t recur.
Other that a warning light being on, a common indication of a throttle body problem can be a rough or unstable idle. If the throttle plate is sticking, or unable to close fully or operate smoothly, that will be most obvious when the vehicle is at idle, in gear, such as stopped for a traffic light.
Generally yes, though the PCM may only allow “limp mode” operation.
Yes. It will usually operate without calibration or re-learning, but the fully-open and fully-closed points may be wrong.
Generally not. Cleaning the throttle plate and bore is the only normal service, and the motor and electronics is usually sealed and non-serviceable.