P2187 System Too Lean at Idle (Bank 1)

Powertrain Severity: Moderate Generic OBD-II

Bank 1 runs lean mostly at idle, which points to an unmetered air leak.

Common causes

  • Vacuum leak
  • Leaking PCV valve
  • Leaking intake gasket

Symptoms

  • Check engine light
  • Rough idle

What to check

  1. Smoke-test the intake
  2. Check PCV system
  3. Watch trims at idle vs cruise

Manufacturers may add their own detail to generic codes. If your vehicle shows a different description for P2187, follow the service information for that make and model.