DTC Troubleshooting: P0139, P0159
DTC P0139: Rear Secondary HO2S (Bank 1, Sensor 2) Slow Response
DTC P0159: Front Secondary HO2S (Bank 2, Sensor 2) Slow Response
NOTE:
Before you troubleshoot, record all freeze data and any on-board snapshot, and 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.
Information marked with an asterisk (*) applies to the front bank (Bank 2).

DTC Description
Confirmed DTC
Pending DTC
Freeze Frame
P0139 Rear Secondary HO2S (Bank 1, Sensor 2) Slow Response
     
P0159 Front Secondary HO2S (Bank 2, Sensor 2) Slow Response
     

1.
Problem verification:

Problem verification
?1.
Press the engine start/stop button to select the ON mode.

?2.
Clear the DTC with the HDS.


?3.
Start the engine. Hold the engine speed at 3,000 rpm without load (A/T in P or N, M/T in neutral) until the radiator fan comes on, then let it idle.

?4.
Test-drive under these conditions:
Engine coolant temperature (ECT SENSOR 1) above 158 °F (70 °C)
A/T in D, M/T in 4th
Drive at a steady speed between 55?75 mph (90?120 km/h) for 1 minute, then decelerate (with the throttle fully closed) for 10 seconds

Signal
Current conditions
Values
Unit
ECT SENSOR 1
    
VEHICLE SPEED
    

?5.
Monitor the OBD STATUS for DTC P0139 and/or P0159* in the DTCs MENU with the HDS.
DTC Description
OBD STATUS
P0139 Rear Secondary HO2S (Bank 1, Sensor 2) Slow Response
 
P0159 Front Secondary HO2S (Bank 2, Sensor 2) Slow Response
 

Does the HDS indicate FAILED?

     
YES
     
     
     
     
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 HDS indicates EXECUTING, keep driving until a result comes on. If the HDS indicates OUT OF CONDITION, go to step 1-3 on this step and recheck.
Repair verification (OBD STATUS check):

?1.
Press the engine start/stop button to select the ON mode.

?2.
Reset the PCM with the HDS.


?3.
Do the PCM idle learn procedure.

?4.
Start the engine. Hold the engine speed at 3,000 rpm without load (A/T in P or N, M/T in neutral) until the radiator fan comes on, then let it idle.

?5.
Test-drive under these conditions:
Engine coolant temperature (ECT SENSOR 1) above 158 °F (70 °C)
A/T in D, M/T in 4th
Drive at a steady speed between 55?75 mph (90?120 km/h) for 1 minute, then decelerate (with the throttle fully closed) for 10 seconds

Signal
Current conditions
Values
Unit
ECT SENSOR 1
    
VEHICLE SPEED
    

?6.
Monitor the OBD STATUS for DTC P0139 and/or P0159* in the DTCs MENU with the HDS.
DTC Description
OBD STATUS
P0139 Rear Secondary HO2S (Bank 1, Sensor 2) Slow Response
 
P0159 Front Secondary HO2S (Bank 2, Sensor 2) Slow Response
 


Does the HDS indicate PASSED, FAILED, EXECUTING, or OUT OF CONDITION?

     
PASSED (P0139)
     
     
     
Troubleshooting is complete. If any other Pending or Confirmed DTCs were indicated, go to the indicated DTC's troubleshooting.?
     
PASSED (P0159)
     
     
     
Troubleshooting is complete. If any other Pending or Confirmed DTCs were indicated, go to the indicated DTC's troubleshooting.?
     
FAILED (P0139)
     
     
     
Go to step 1 and recheck.
     
FAILED (P0159)
     
     
     
Go to step 1 and recheck.
     
EXECUTING
     
     
     
Keep the test condition until a result comes on.
     
OUT OF CONDITION
     
     
     
Meet the test condition, and check the OBD STATUS again.