DTC P0139: Secondary Heated Oxygen Sensor (Ho2S-2) Slow Response

Perform PCM reset procedure. See PCM RESET PROCEDURE/CLEARING CODES . 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 speed at 3000 RPM. If voltage does not stay at 0.3-0.6 volt for 2 minutes, problem is intermittent, system is functioning properly at this time. Check for poor connections or loose wires between HO2S-2 and PCM connectors. See the WIRING DIAGRAMS article. Repair as necessary. If voltage stays at 0.3-0.6 volt for 2 minutes, replace HO2S-2.