2013 Subaru Forester - Intermittent Stalling (No Codes)

[theresemc]

I have a 2013 Subaru Forester non turbo. At the beginning of March, my car started stalling about once a week. After it stalled the first time, I got new spark plugs and two weeks later, I replaced the catalytic converter (per the codes on my dashboard.) After fixing both of these things, my car is still stalling about 1-2 times a week. Here are the dates it stalled and conditions:

3/9 - Stalled at a red light off of a highway exit. Started back up after about 10-15 minutes.
3/15 - Got new spark plugs and general maintenance. Drove it a few miles after to the gas station to fill up the tank. Stalled immediately after starting it, but then turned on as normal and drove home normal.
3/29 - Replaced the catalytic converter (per the dashboard codes.) Stalled about 15-20 minutes after leaving the mechanic. Started back up after about 5 minutes.
4/3 - Stalled at a red light off of a highway exit. Started back up after about 10-15 minutes. NO CODES
4/10 - Installed new PCV valve and cleaned out idle air control valve. Stalled at a red light off of a highway exit. Started back up after about 10-15 minutes. NO CODES
4/11 - Stalled at a red light off of a highway exit. Started back up after about 10-15 minutes. NO CODES
4/18 - Did an idle relearn. Did not stall.
4/24 - Got transmission fluid flushed and replaced, along with a new filter. Stalled at a stop sign, but this time started right back up without issue. NO CODES

I have about an hour commute one way to work 5 days a week, so roughly 2 hours of driving per day. Car has 153K miles on it, oil changes are always on time, regular maintenance and inspection. Looking to see if anyone has any suggestions on what might be causing the intermittent stalling without codes. We also tried doing a live scan, but since it's random, they weren't able to get my car to stall, so no codes were shown.

Thank you!

 

[Ecmbuster]

No codes means you're using an OBD II scan tool.
Either there is NO data display on the scan tool or there is data, therefore >>
Use that scan tool with either Android or iOS but record the screen.
If the engine controller looses communication, the OBD II scan tool with display a notice.
That Subaru uses the SSM protocol (Subaru Select Monitor) meaning, there are many controllers using the SSM protocol
Test the battery and charging system.
Inspect all ground points from the battery negative post to the body, check and inspect all the body ground straps.
Check and monitor the fuel pressure (safely).
Make sure the ignition switch is not worn (open circuit).
Clean and recheck the throttle body and throttle pedal signals.
If all tests pass, apply the procedure below.

When the ECM is Reset and all DTC's have been cleared, the ECM idle control is also cleared.
If you have SSM3 or SSM4, simply instruct the ECM to set the idle speed.
Aftermarket bi-directional scan tools should be able to adapt the throttle program.
If there is no access to a factory style scan tool, you can recreate the proper conditions for the ECM to relearn idle control and the correct RPM to maintain idle speed under load conditions.
Load conditions include:
Cooling fans ON or OFF
A/C request
Power Steering load request
Transmission load request
Any electrical load request
Procedure:
1. Ensure all power accessories ie: lighting, heater and electrical parasites are OFF.
2. Disconnect the battery negative for 30 minutes.
3. Reconnect the battery negative.
4. Following all steps without touching any switches or pedals. Use the ignition key only.
5. Insert key to the ON position only for 20 seconds.
6a. Turn the key so that the engine starts.
6b. Set timer for 20 minutes.
6c. Let engine idle for 20 minutes.
7. Turn key OFF and leave the key in ignition for 20 seconds.
8. Remove the key.
9. Repeat step 5 and Continue to step 10a when complete.
10a. Turn the key so the engine starts and set timer for 10 minutes.
10b. Let engine idle for 10 minutes.
11. Turn the key OFF and leave key in ignition for 20 seconds.
12. Remove the key. The ECM has relearned idle speed.

Reset the clock, radio stations and electric window one-trip features.
At times, the memory electric seats and remote fobs may not operate. A reset is required.

 

[theresemc]

No codes means you're using an OBD II scan tool.
Either there is NO data display on the scan tool or there is data, therefore >>
Use that scan tool with either Android or iOS but record the screen.
If the engine controller looses communication, the OBD II scan tool with display a notice.
That Subaru uses the SSM protocol (Subaru Select Monitor) meaning, there are many controllers using the SSM protocol
Test the battery and charging system.
Inspect all ground points from the battery negative post to the body, check and inspect all the body ground straps.
Check and monitor the fuel pressure (safely).
Make sure the ignition switch is not worn (open circuit).
Clean and recheck the throttle body and throttle pedal signals.
If all tests pass, apply the procedure below.

When the ECM is Reset and all DTC's have been cleared, the ECM idle control is also cleared.
If you have SSM3 or SSM4, simply instruct the ECM to set the idle speed.
Aftermarket bi-directional scan tools should be able to adapt the throttle program.
If there is no access to a factory style scan tool, you can recreate the proper conditions for the ECM to relearn idle control and the correct RPM to maintain idle speed under load conditions.
Load conditions include:
Cooling fans ON or OFF
A/C request
Power Steering load request
Transmission load request
Any electrical load request
Procedure:
1. Ensure all power accessories ie: lighting, heater and electrical parasites are OFF.
2. Disconnect the battery negative for 30 minutes.
3. Reconnect the battery negative.
4. Following all steps without touching any switches or pedals. Use the ignition key only.
5. Insert key to the ON position only for 20 seconds.
6a. Turn the key so that the engine starts.
6b. Set timer for 20 minutes.
6c. Let engine idle for 20 minutes.
7. Turn key OFF and leave the key in ignition for 20 seconds.
8. Remove the key.
9. Repeat step 5 and Continue to step 10a when complete.
10a. Turn the key so the engine starts and set timer for 10 minutes.
10b. Let engine idle for 10 minutes.
11. Turn the key OFF and leave key in ignition for 20 seconds.
12. Remove the key. The ECM has relearned idle speed.

Reset the clock, radio stations and electric window one-trip features.
At times, the memory electric seats and remote fobs may not operate. A reset is required.

Thank you for taking the time to reply! We will definitely be trying these tests and this procedure!