Press Sauté; heat oil in Instant Pot®. Add potatoes, leeks, celery, fennel, bell pepper, thyme, salt and black pepper; cook about 8 minutes or until vegetables are slightly softened, stirring occasionally. Add flour; cook and stir 1 minute. Add clam juice and water; mix well.
Secure lid and move pressure release valve to Sealing position. Press Manual or Pressure Cook; cook at high pressure 6 minutes.
When cooking is complete, press Cancel and use quick release. Use immersion blender to blend soup just until slightly thickened (soup should not be completely smooth).
Press Sauté; add cod, corn, half-and-half and parsley to pot. Cook about 2 minutes or until soup begins to simmer and fish is firm and opaque, stirring occasionally.