How to clean a throttle body yourself — step by step

To clean a throttle body yourself, use carburettor cleaner: it dissolves carbon, varnish deposits and dirt. Work on a cold engine with the ignition off. For routine cleaning, the throttle body stays in place; for heavy deposits, remove it, apply the cleaner to each part, leave it for 5 minutes and remove the carbon with a cloth or brush.

What you need

Cleaner for carburetor, 400 ml

For carburettors and throttle bodies

Why clean the throttle body

Carbon, deposits and dirt gradually build up on the throttle valve and in the fuel system passages, narrowing the air path, so the idle can become unstable. Carburettor cleaner removes deposits from throttle valves, air and fuel jets, carburettor and injector passages and the idle circuit. It suits two- and four-stroke petrol engines with or without a catalytic converter. For maximum effect, repeat the cleaning every 5,000–10,000 km.

How to clean a throttle body — step by step

1. Switch off the engine and let it cool. Keep the ignition off until the job is done. Wear gloves and work outdoors or in a well-ventilated area at +5 °C or above.
2. Get access to the throttle valve. Loosen the clamp and disconnect the air intake hose. Unplug the sensor and actuator connectors or cover them with a rag: keep the cleaner off them. For routine cleaning, nothing else needs removing.
3. Apply the cleaner. Shake the can of NANOPROTECH Carburettor cleaner and spray the throttle valve and the bore walls. Let it soften the deposits — no longer than the 5 minutes set for heavy deposits.
4. Remove the carbon. Wipe it off with a cloth or brush and repeat if needed. Do not force an electronic throttle open or switch on the ignition to open it: this can damage the actuator.
5. For heavy deposits, remove the unit. Take it off as the vehicle manual describes — this also gives access to the back of the valve. Apply the cleaner to the housing and valve, leave it for 5 minutes and remove the carbon with a cloth or brush. Keep the actuator and throttle position sensor dry; remove rubber seals while cleaning.
6. Let the cleaner evaporate. It evaporates quickly and leaves no film, so no rinsing with water is needed; the passages of a removed unit can be blown through with compressed air. Wipe any drops off rubber, plastic and painted parts at once.
7. Reassemble and start the engine. Reconnect the plugs and refit the hose once the cleaner has fully evaporated. At first the idle may differ from usual while the engine control unit adapts to the clean throttle. If it does not settle, carry out a throttle adaptation as per the vehicle manual or at a garage.

If a fastener will not budge when you remove the unit, see how to remove a seized bolt.

Why it may not work

• Carbon remains after routine cleaning. Cleaning in place is for routine maintenance. Heavy deposits need the unit removed and a 5-minute dwell on each part before the carbon is wiped off.
• The cleaner was wiped off at once or used in the cold. It needs time to soften deposits and is applied at +5 °C or above. Always shake the can first.
• The idle hunts after cleaning. The control unit needs an adaptation. If the idle is still unstable afterwards, carbon is not the cause — have the car diagnosed.

Safety precautions

• The can is pressurised and the product is flammable. Do not spray it on a running or hot engine, with the ignition on, or near open flames, red-hot objects or live electrical equipment.
• Do not pour the cleaner into the fuel tank: it is not a fuel additive. Keep it off sensors and connectors, and do not leave it on rubber, plastic or paintwork.
• Keep the can out of direct sunlight and do not heat it above 50 °C; do not pierce or burn it, even when empty.
• Work with good ventilation. In case of eye contact, rinse with water; on skin, wash with soap and water. Keep out of the reach of children.

Frequently asked questions