DTC P0139
DTC P0139: Rear Secondary Heated Oxygen Sensor (Secondary HO2S (Bank 1, Sensor 2)) Slow Response
General Description
The rear secondary heated oxygen sensor (secondary HO2S (Bank 1, Sensor 2)) detects the oxygen content in the exhaust gas downstream of the rear warm up three way catalytic converter (WU-TWC) (bank 1) during stoichiometric air/fuel ratio feedback control. The powertrain control module (PCM) controls the air/fuel ratio with the rear air/fuel ratio (A/F) sensor (Bank 1, Sensor 1) output voltage to optimize the rear WU-TWC (bank 1)'s efficiency. When the rear secondary HO2S (Bank 1, Sensor 2) does not change during lean air/fuel ratio when the throttle is closed, after full current is applied to the rear secondary HO2S (Bank 1, Sensor 2) heater, and output remains within the specified range continuously, the PCM detects a malfunction and stores a DTC.
Monitor Execution, Sequence, Duration, DTC Type
| Execution | Once per driving cycle |
| Sequence | P0138 is judged as OK |
| Duration | 8.0 seconds or more |
| DTC Type | Two drive cycles, MIL on |
Enable Conditions
| Condition | Minimum | Maximum |
|---|---|---|
| Elapsed time after starting the engine | 2 minutes | - |
| Engine coolant temperature [ECT SENSOR 1] | 156 deg.F (69 deg.C) | - |
| Intake air temperature [IAT SENSOR] | -13 deg.F (-25 deg.C) | - |
| Engine speed [ENGINE SPEED] | - | 4000 RPM |
| Secondary HO2S output voltage [HO2S B1 S2] | 0.05 V | - |
| Intake air amount*1 | 0.07 oz/second (2 g/second) | - |
| Fuel feedback | During deceleration | |
*1: 2016 model on and after
[ ]: HDS Parameter
Malfunction Threshold
The rear secondary HO2S (Bank 1, Sensor 2) output voltage [HO2S B1 S2] is 0.05 V or more for at least 8.0 seconds.
Possible Cause
- Rear secondary HO2S (Bank 1, Sensor 2) responsive deterioration
- Exhaust system failure (exhaust gas leak)
Confirmation Procedure
Operating Condition
- 1.
Start the engine. Hold the engine speed [ENGINE SPEED] at 3000 RPM without load (in P or N) until the radiator fan comes on.
- 2.
Drive the vehicle at a steady speed between 55 - 75 mph (88 - 120 km/h) for at least 1 minute.
- 3.
Decelerate with the throttle valve fully closed for at least 8 seconds.
- Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.
With the HDS
None.
Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle, the MIL comes on and a Confirmed DTC and the freeze data are stored.
Conditions for clearing the DTC
The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the battery.