DTC Advanced Diagnostics: P0137 (3.0L Engine)

DTC P0137: Secondary Heated Oxygen Sensor (Secondary HO2S (Sensor 2)) Circuit Low Voltage

General Description

Courtesy of HONDA, U.S.A., INC.

The secondary heated oxygen sensor (secondary HO2S (sensor 2)) detects the oxygen density in the exhaust gas and converts it into electrical signals. If the secondary HO2S (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

Execution	Continuous
Sequence	None
Duration	1 second or more
DTC Type	Two drive cycles, MIL on

Enable Conditions

Condition	Minimum	Maximum
Elapsed time after starting the engine	1 minute 40 seconds	-
12 volt battery voltage [Battery]*	10.0 V	-

*: Maintain for 2.5 seconds or more[ ]: HDS Parameter

Malfunction Threshold

Short to ground detection
The SO2SG terminal voltage is 0.210 V or less for at least 1 second after the vehicle is turned to the ON mode for 2.5 seconds.
Open circuit detection
The SO2 terminal voltage is 0.826 V or less and SO2SG terminal voltage is between 1.704 V - 2.306 V for at least 1 second after 5 seconds from the engine run for 1 minute 40 seconds (duty integration value of 60, 500 % (integrating per 50 milliseconds)).

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.

Secondary HO2S (sensor 2) SO2 line short to ground
Secondary HO2S (sensor 2) SO2 line open
Secondary HO2S (sensor 2) SO2SG line short to ground
Secondary HO2S (sensor 2) SO2SG line open
PCM internal circuit failure

Confirmation Procedure

Operating Condition

Start the engine. Hold the engine speed [Engine Speed] at 3, 000 rpm without load (in P or N) until the radiator fan comes on, then let it idle.

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, the freeze data, and the on-board snapshot 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, the freeze data, and the on-board snapshot can be cleared with the scan tool clear command.