Codex FAQ

Use the latest model in Codex

Recommended method

1. Open config.toml and locate model = "gpt-xxx".
2. Change it to model = "gpt-5.6-sol" and save the file.
3. Restart Codex CLI, the Codex app, or the VS Code extension.
4. Do not switch models inside the active session.

For Codex CLI, start a fresh session with:

codex -m gpt-5.6-sol -c model_reasoning_effort="ultra"

If Codex is already running, press Ctrl + C before restarting it.

VS Code extension

The replacement package below targets Codex extension version v26.5707.31428.

1. Switch the Codex extension to its pre-release channel.
2. Open the VS Code extension directory.

Windows

start "" "%userprofile%\.vscode\extensions"

macOS

open "$HOME/.vscode/extensions"

3. Find the directory beginning with openai.chatgpt-26.5707.31428-.
4. Open its webview/assets directory.
5. Download the archive below, extract it, and replace the existing JavaScript file.

Supported Codex extension version v26.5707.31428

Updated for the latest GPT-5.6 model family.

vscode-codex-replace.zipZIP archive

Download

6. Restart VS Code and check the model list.