Choke Symbol For Lawn Mower: Know How to Use It Correctly

By Desmond J.

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If you’ve recently purchased a lawn mower, you might have noticed the choke symbol on its control panel, which can be puzzling.

Let’s clarify what the choke symbol means and how to use it effectively. Whether you’re well-versed in lawn mower operation or a novice, we’ll provide a straightforward explanation of the choke symbol’s purpose and how to use it properly.

What Is a Choke Symbol?

The choke symbol on your lawn mower plays a crucial role in managing the air-fuel mixture within the engine, especially during startup in cold weather conditions. This symbol or control mechanism optimizes engine performance and facilitates easier starting.

When the choke is set to the “On” position, it restricts airflow into the carburetor, resulting in a richer mixture with more fuel and less air. This enriched mixture is easier to ignite and generates the necessary heat to initiate the engine when it’s cold outside. Essentially, the choke symbol restricts airflow, ensuring the fuel-air ratio is ideal for cold starts.

Conversely, shifting the choke to the “Off” position allows air to flow freely into the carburetor, creating a leaner mixture suitable for regular operation. This adjustment is made once the engine has warmed up and can run smoothly without the need for extra fuel.

Typically associated with a metal plate attached to the choke lever, activating the choke symbol by moving the lever to the “On” position restricts airflow while moving it to the “Off” position permits unrestricted airflow.

How To Read Choke Symbols

Choke symbols on lawn mowers typically feature two distinct positions: “On” and “Off,” each signifying a specific setting for the choke. It is crucial to comprehend how to interpret the unique symbols on your specific mower model.

These symbols may differ from one mower model to another, making it vital to grasp the precise significance of the symbols on your equipment.

Below, we delve into various choke symbols and their corresponding meanings to help you understand them better.

“O” Symbol With a Line: “On” Position

In the lawn mowers, choke symbols can vary, but they generally consist of two positions: “On” and “Off,” representing the choke settings. For some mowers, an “O” symbol with additional lines is used. If you see an “O” with a horizontal or diagonal line, it means the choke is “On,” indicating restricted airflow for starting.

Conversely, an “O” with a vertical line signifies the choke is “Off,” allowing normal airflow. Another common pair of symbols on lawnmowers is the rabbit (open choke for operation) and turtle (closed choke for starting), indicating the choke’s status.

These symbols help users easily identify and adjust the choke as needed for different phases of engine operation.

Rabbit and Turtle Symbol

The rabbit symbol signifies that the choke is open, allowing unrestricted airflow. This indicates that the engine is prepared for regular operation.

Conversely, the turtle symbol indicates that the choke is closed, regulating airflow to ensure a consistent flow of fuel into the engine, enabling it to start.

These symbols are commonly used to indicate the choke’s status and assist users in easily understanding and adjusting it according to the engine’s needs.

“I” and “O” Choke Symbol

Some lawnmowers are equipped with choke symbols that include an “I” and “O” in conjunction with a red or blue switch positioned between them. These symbols and switches serve to control the choke’s status and airflow. Let’s delve into the specifics of how these symbols function and the possible alternatives for choke labels on different lawnmower models:

“I” Position (Choke On or Closed): When the switch is set to “I,” it indicates that the choke is engaged or in the closed position. This setting restricts airflow into the carburetor, creating a richer fuel-air mixture. It’s particularly useful when starting the engine in cold weather conditions because the enriched mixture is easier to ignite. To start the engine, move the switch to “I” when temperatures are low.

“O” Position (Choke Off or Open): In contrast, when the switch is set to “O,” it signifies that the choke is disengaged or in the open position. This allows unrestricted airflow into the carburetor, creating a leaner fuel-air mixture suitable for regular operation. You should move the switch to “O” when the engine has sufficiently warmed up and is ready for standard operation.

While the “I” and “O” symbols are common, not all lawnmower models use them. Some mowers feature alternative labels for their choke controls:

  • “Open/Close”: “Open” indicates the choke is off, while “Close” suggests that the choke is on.
  • “On/Off”: “On” signifies that the choke is engaged (closed), while “Off” means that the choke is disengaged (open).
  • “Start/Closed”: “Start” implies that the choke is on, while “Closed” indicates that the choke is off.
  • “Full Choke/Run”: “Full Choke” or simply “Choke” signifies that the choke is engaged or closed to restrict airflow, while “Run” indicates that the choke is disengaged or open.

For lawnmowers with twin-cylinder engines, you might encounter an additional “Half Choke” label located between the “Full Choke” and “Run” labels. “Half Choke” suggests that the choke is partially open or closed. This setting is designed to prevent the mower from stalling when transitioning from “Run” to “Full Choke.”

If your lawnmower doesn’t have a “Half Choke” label and you’re uncertain about which choke setting to use, positioning the choke lever between “Full Choke” and “Run” allows the engine to adapt gradually to reduced airflow.

Should you find interpreting these choke symbols confusing, it’s advisable to consult your lawnmower’s owner’s manual. The manual typically provides detailed information about the meaning of each choke symbol and the recommended choke lever position for starting and operating your specific mower model.

How Does A Choke Work On A Lawn Mower

A choke on a lawn mower works by adjusting the air-to-fuel ratio in the engine’s carburetor to make it easier to start a cold engine. Here’s how it operates:

Normal Operation: When the engine is running at operating temperature, it requires a specific balance of air and fuel for optimal combustion. In this condition, the choke is typically in the “Off” or “Open” position. This allows a normal amount of air to enter the carburetor, resulting in a lean air-fuel mixture.

Starting a Cold Engine: When you start a lawnmower with a cold engine, the air and fuel mixture need to be richer (more fuel and less air) to ignite easily. This is where the choke comes into play. When you engage the choke by moving the lever or knob to the “On” or “Closed” position, it restricts the amount of air entering the carburetor.

Rich Mixture: With the choke on, the engine receives a reduced amount of air, creating a rich air-fuel mixture. This rich mixture is easier to ignite because it contains more fuel, making the engine start more readily, especially in cold conditions.

Warming Up: Once the engine has started and begins to warm up, the choke should be gradually moved to the “Off” or “Open” position. This allows more air to enter the carburetor, shifting the mixture back to the normal, leaner ratio suitable for efficient and smooth operation.

The choke temporarily alters the air-fuel mixture to favor richer combustion when starting a cold lawn mower engine. Once the engine is running smoothly and has warmed up, the choke should be returned to the “Off” position to achieve the correct air-fuel ratio for optimal performance.

Choke Location of The Lawn Mower

The location of the choke on lawn mowers can vary depending on the make and model of the mower. However, we can provide you with a general guide to where to look for the choke lever or knob.

  1. Under the Air Filter Cover: Often, the choke lever or knob can be found beneath the air filter cover. To access it, you might need to remove a cover or access panel.
  2. On the Engine: Some mowers have the choke control directly on the engine, usually near the carburetor. It may be on the side or top of the engine.
  3. On the Handlebar: On certain models, the choke control is on the handlebar of the mower for convenient access while operating.
  4. Integrated with Throttle Control: In newer models, the choke control may be part of the throttle control. To engage the choke, you would move the throttle lever to a specific “choke” position.
  5. Refer to the Owner’s Manual: If you’re uncertain about where to find the choke on your specific mower, consult the owner’s manual that came with the mower. It will contain precise instructions regarding the choke’s location and how to use it.

Remember, the choke is used to adjust the air-fuel mixture when starting a cold engine to facilitate easier starting. After the engine warms up, you typically need to return the choke to the “run” or “normal” position for regular operation.

Can You Operate a Lawn Mower With the Choke On?

You can technically operate a lawnmower with the choke on, but it’s not advisable for normal mowing. The choke is primarily used when starting a cold engine to provide a richer fuel mixture, which makes it easier to start. Once the engine is running smoothly and has warmed up, you should typically move the choke to the “run” or “normal” position.

Leaving the choke on while mowing can cause the engine to run too rich (too much fuel and not enough air), leading to several issues:

  1. Reduced Performance: The engine may not perform at its best, resulting in decreased power and cutting efficiency.
  2. Excessive Fuel Consumption: Running with the choke on consumes more fuel than necessary, leading to higher operating costs.
  3. Carbon Buildup: Over time, excessive fuel can cause carbon buildup on spark plugs and other engine components, potentially reducing their lifespan.
  4. Increased Emissions: Operating with the choke on generates more emissions, which is not environmentally friendly.

While you can use the choke to start a cold lawnmower engine, it’s best to turn it off once the engine warms up for peak performance, fuel efficiency, and engine lifespan.

When Should You Run the Lawn Mower With the Choke On?

You might choose to run your lawn mower with the choke on in the following situations:

  1. Fuel Line or Filter Blockage: If there’s a blockage in the fuel line or filter that restricts fuel flow to the carburetor.
  2. Suboptimal Fuel Mixture: When the fuel in the tank has a less-than-optimal octane mixture, often due to water or additives in the fuel.

Before operating your mower in these cases, address the issues by clearing the fuel line, replacing the filter, or resolving fuel mixture problems, such as draining and refilling the tank with fresh fuel.


Understanding the choke symbol on your lawn mower is essential for smooth operation. Choke symbols can vary between machines.

When you see a closed symbol, it means the choke is on, regulating airflow to assist with engine startup, particularly in colder conditions.

On the other hand, an open symbol indicates that the choke is off, allowing unrestricted airflow. After the engine has warmed up, turning off the choke ensures efficient mower operation.

Kindly consider sharing this valuable insight with your fellow lawn maintenance enthusiasts, allowing them to enhance their mowing proficiency.

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Written By
Desmond J.
I'm a lawn mowing expert and gardening enthusiast. I started my own lawn care business in college and have been doing it ever since. I love taking care of lawns and gardens, and I'm always looking for new ways to improve my skills. I'm also a big fan of composting and using natural fertilizers.

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