DTC P0139: Secondary Ho2S-2 Slow Response

Perform PCM reset procedure. See SELF-DIAGNOSTICS - INTRODUCTION article. Start engine and run at 3000 RPM with no loads and transmission in Park or Neutral until radiator fan comes on. Using scan tool, check HO2S-2 output voltage with engine at 3000 RPM. If output voltage stays at 0.3-0.6 volt for 2 minutes, replace HO2S-2. If output voltage does not stay at 0.3-0.6 volt for 2 minutes, problem is intermittent. System is okay at this time. Check for poor connections or loose wires at HO2S-2 and PCM connectors. Also check for poor connections or loose wires at Green, 22-pin C127 connector, located behind right kick panel, on PCM bracket. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary.