DTC Troubleshooting: P0139
DTC P0139: Secondary HO2S (Sensor 2) Slow Response
NOTE:
Before you troubleshoot, review the general troubleshooting information.
If there are leaks from the exhaust system, this DTC will be set. Check for damage in the exhaust pipe and repair it if needed.

DTC Description
Confirmed DTC
Pending DTC
P0139 Secondary HO2S (Sensor 2) Slow Response
    

1.
Problem verification:

Problem verification
?1.
Turn the vehicle to the ON mode.

?2.
Clear the DTC with the HDS.


?3.
Start the engine.

?4.
Hold the engine speed at 3,000 rpm without load (in neutral) until the radiator fan comes on, then let it idle.

?5.
Test-drive the vehicle for several minutes in the range of these recorded on-board snapshot parameters:
Engine Speed
Vehicle Speed
ECT Sensor 1
Signal
Current conditions
Values
Unit
Engine Speed
    
Vehicle Speed
    
ECT Sensor 1
    

?6.
Monitor the OBD STATUS for DTC P0139 in the DTCs MENU with the HDS.
DTC Description
OBD STATUS
P0139 Secondary HO2S (Sensor 2) Slow Response
  

Does the HDS indicate FAILED?

     
YES
     
     
     
The failure is duplicated. Replace secondary HO2S (Sensor 2).?
     
NO
     
     
     
If the HDS indicates PASSED, intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at secondary HO2S (Sensor 2) and the PCM. If the on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the on-board snapshot. If the HDS indicates EXECUTING, keep driving until a result comes on. If the HDS indicates OUT OF CONDITION, go to step 1-4 and recheck.?