Subaru Throttle Body Relearn: A Step by Step Guide

How to Perform a Subaru Throttle Body Relearn Procedure on a Subaru with an Electronic Throttle Body

If you own a Subaru with an electronic throttle body (ETB), you may find yourself needing to perform a throttle body relearn procedure at some point. This can

Typical Subaru Throttle Body

happen after cleaning the throttle body, replacing the throttle body, disconnecting the battery, or performing certain engine repairs. When the throttle body loses its learned position, it can cause rough idling, stalling, or even poor throttle response. Fortunately, the relearn process is relatively straightforward. I’ve done this myself on a few Subaru models, and I’ll walk you through the step-by-step process to get your vehicle running smoothly again.

What Most DIYers Do Wrong

1) They don’t wipe out the adaptive memory
2) They don’t turn off all electrical accessories before and during the relearn procedure.

Why It’s Important to Wipe The Adaptive Memory

The adaptive memory holds all the modifications the ECM has made to factory programming to account for a dirty electronic throttle body and engine wear. If you’re cleaning or replacing the throttle body and you don’t wipe the adaptive memory, it will try and start the engine using the previous throttle body settings. So I recommend starting the procedure by wiping out the adaptive memory and starting fresh. There are two ways to do this:

1) Disconnect the battery negative terminal and leave it off for at least 10 minutes or
2) Disconnect both battery terminals and touch them together for 3-5 minutes. This drains the capacitors in the ECM and wipes out the adaptive memory.

Turn Off ALL Electrical Loads

Turning off all electrical loads ensures you get a clean, no-load idle setting. This means no radio, headlights, seat heaters, fan, or AC. Do this before you even start the procedure.

Step 1 to Perform a Subaru Throttle Body Relearn

Turn the key to the ON position and leave it there for 10-15 seconds. You’ll hear the electronic throttle body hum, buzz, or click while it performs several sweeps to find the full open and closed positions after 15 seconds or when the noise stops. Leave the key in the ON position and move to Step 2.

Step 2: Start the Engine for 10 Minutes

Turn the key to the start position and start the engine. In this portion of the procedure, you’ll let it run for 10 minutes. During this period, don’t turn on any electrical accessories. Just let it run in idle. Use the timer on your watch or phone. Don’t touch the accelerator pedal during this time. You may hear the engine rev up and down. That’s normal.

Step 3: A Quick Turn Off

In this next portion of the Subaru throttle body relearn, you’ll turn the key to the OFF position for 20 seconds. After 20 seconds, turn the key back to the ON position, but don’t start the engine! Leave it in the ON position for 10-15 seconds for the throttle body to cycle through the sweeps again.

Step 4: Start the Engine Again

After 15 seconds in the ON position, and without turning the key to the OFF position, start the engine again. This time, let it idle for 5 minutes.

Step 5: Turn Off The Engine And Leave it Off For 20 Seconds Before Taking It On a Test Drive

After 20 seconds in the OFF position, turn the key to start the engine. Then, take it for a test drive on city streets with stop signs/lights and then make a short trip on the highway.

The Subaru Throttle Body Relearn should not be complete, but you should have a smooth idle. Keep in mind that over the next 10 starts, the ECM will continue to relearn all the adaptive settings it needs to run smoothly and get the best MPG.

©, 2025 Rick Muscoplat