DTC Advanced Diagnostics: P0157
DTC P0157:Front Secondary Heated Oxygen Sensor (Secondary HO2S (Bank 2, Sensor 2)) Circuit Low Voltage

General Description

The front secondary heated oxygen sensor (secondary HO2S (bank 2, sensor 2)) detects the oxygen density in the exhaust gas and converts it into electrical signals. If the front secondary HO2S (bank 2, sensor 2) output voltage is a specified value for a set time, the powertrain control module (PCM) detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type, OBD Status
Execution
Continuous
Sequence
None
Duration
5 seconds or more
DTC Type
Two drive cycles, MIL on
OBD Status
PASSED/FAILED/EXECUTING/OUT OF (TEST) CONDITION

Enable Conditions
Condition
 
State of the engine
Running
Other
At least 55 seconds must be passed after the front secondary HO2S (bank 2, sensor 2) output voltage reaches 1.0 V or less

Malfunction Threshold
The front secondary HO2S (bank 2, sensor 2) output voltage [HO2S B2 S2] is 0.18 V or less for at least 5 seconds.

[ ]: HDS Parameter

Possible Cause
NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
Front secondary HO2S (bank 2, sensor 2) SO2B2 line short to ground
Front secondary HO2S (bank 2, sensor 2) SO2SGB2 line short to ground
PCM internal circuit failure

Confirmation Procedure
Operating Condition
Start the engine. Hold the engine speed [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.

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.