DTC P0139: Secondary Ho2S-2 Slow Response

Perform PCM reset procedure. See PCM RESET PROCEDURE/CLEARING CODES  under SELF-DIAGNOSTIC SYSTEM. Start engine and run at 3000 RPM, with no load and transmission in Park or Neutral, until radiator fan comes on. Using scan tool, check HO2S-2 output data while running engine at 3000 RPM. If voltage stays within 0.3-0.6 volt for 2 minutes, replace HO2S-2. If voltage does not stay within 0.3-0.6 volt for 2 minutes, problem is intermittent. System is okay at this time. Check for poor connections or loose wires between HO2S-2 and PCM. See WIRING DIAGRAMS article.