DTC P0139 [LF]: Notes

DTC P0139 (LF) DETECTION CONDITION AND POSSIBLE CAUSE

DTC P0139	HO2S circuit slow response
DETECTION CONDITION	The PCM monitors the rich (0.55 V) to lean (0.3 V) response time of the HO2S. The PCM measures the response time when the following conditions are met. The PCM determines a HO2S response deterioration malfunction when the measured response time is more than 110 ms for 2 of 3 times . MONITORING CONDITIONS PCM Adaptive Memory Production, EGR System, A/F Sensor Heater, HO2S Heater, A/F Sensor, HO2S, and TWC Repair Verification Drive Mode Following conditions are met: During deceleration fuel cut Estimated temperature of the zirconia element inside the HO2S: above 450°C {842°F} The PCM monitors for a time-out malfunction (when HO2S remains above 0.2 V for longer than a specified period of time during fuel cut control). The PCM measures the amount of time from when the following conditions are met until the HO2S output voltage drops below 0.2 V . The PCM determines a HO2S timeout malfunction when the detected time is more than 4 s for 2 of 3 times . MONITORING CONDITIONS PCM Adaptive Memory Production, EGR System, A/F Sensor Heater, HO2S Heater, A/F Sensor, HO2S, and TWC Repair Verification Drive Mode Following conditions are met: During deceleration fuel cut Estimated temperature of the zirconia element inside the HO2S: above 450°C {842°F} Diagnostic support note This is an intermittent monitor (A/F sensor, HO2S). The MIL illuminates if the PCM detects the above malfunction condition in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM. PENDING CODE is available if the PCM detects the above malfunction condition during the first drive cycle. FREEZE FRAME DATA (Mode 2/Mode 12) is available. The DTC is stored in the PCM memory.
POSSIBLE CAUSE	HO2S malfunction HO2S connector or terminals malfunction Looseness HO2S Leakage exhaust system HO2S deterioration Fuel supply system malfunction or improper fuel line pressure Fuel leakage on fuel line from fuel distribution pipe and fuel pump Fuel filter (built-in fuel pump unit) clogged or restricted Pressure regulator (built-in fuel pump unit) malfunction Fuel pump malfunction Purge system malfunction Purge solenoid valve malfunction Purge solenoid hoses improper connection Engine malfunction Leakage engine coolant to combustion chamber Insufficient compression PCM malfunction

DTC P0139

HO2S circuit slow response

DETECTION CONDITION

The PCM monitors the rich (0.55 V) to lean (0.3 V) response time of the HO2S. The PCM measures the response time when the following conditions are met. The PCM determines a HO2S response deterioration malfunction when the measured response time is more than 110 ms for 2 of 3 times .
MONITORING CONDITIONS
- PCM Adaptive Memory Production, EGR System, A/F Sensor Heater, HO2S Heater, A/F Sensor, HO2S, and TWC Repair Verification Drive Mode
- Following conditions are met:
  - During deceleration fuel cut
  - Estimated temperature of the zirconia element inside the HO2S: above 450°C {842°F}
The PCM monitors for a time-out malfunction (when HO2S remains above 0.2 V for longer than a specified period of time during fuel cut control). The PCM measures the amount of time from when the following conditions are met until the HO2S output voltage drops below 0.2 V . The PCM determines a HO2S timeout malfunction when the detected time is more than 4 s for 2 of 3 times .
MONITORING CONDITIONS
- PCM Adaptive Memory Production, EGR System, A/F Sensor Heater, HO2S Heater, A/F Sensor, HO2S, and TWC Repair Verification Drive Mode
- Following conditions are met:
  - During deceleration fuel cut
  - Estimated temperature of the zirconia element inside the HO2S: above 450°C {842°F}

Diagnostic support note

This is an intermittent monitor (A/F sensor, HO2S).
The MIL illuminates if the PCM detects the above malfunction condition in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM.
PENDING CODE is available if the PCM detects the above malfunction condition during the first drive cycle.
FREEZE FRAME DATA (Mode 2/Mode 12) is available.
The DTC is stored in the PCM memory.

POSSIBLE CAUSE

HO2S malfunction
- HO2S connector or terminals malfunction
- Looseness HO2S
- Leakage exhaust system
- HO2S deterioration
Fuel supply system malfunction or improper fuel line pressure
- Fuel leakage on fuel line from fuel distribution pipe and fuel pump
- Fuel filter (built-in fuel pump unit) clogged or restricted
- Pressure regulator (built-in fuel pump unit) malfunction
- Fuel pump malfunction
Purge system malfunction
- Purge solenoid valve malfunction
- Purge solenoid hoses improper connection
Engine malfunction
- Leakage engine coolant to combustion chamber
- Insufficient compression
PCM malfunction