DTC Advanced Diagnostics: P0038 (3.0L Engine)

DTC P0038: Secondary Heated Oxygen Sensor (Secondary HO2S (Sensor 2)) Heater Circuit High Voltage

General Description

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

The secondary heated oxygen sensor (secondary HO2S (sensor 2)) heater is controlled by the duty signal command from the powertrain control module (PCM) to heat the secondary HO2S (sensor 2) to an optimal temperature. The output driver circuit in the PCM monitors the voltage level of the SO2HT terminal, and if the voltage level of the SO2HT terminal is OFF (high voltage) despite the PCM outputs ON signal to the secondary HO2S (sensor 2) or if the PCM detects over current of the secondary HO2S (sensor 2) while the PCM outputs ON signal to the secondary HO2S (sensor 2), the PCM detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type

Execution	Continuous
Sequence	None
Duration	5 seconds or more
DTC Type	Two drive cycles, MIL on

Enable Conditions

Condition	Minimum	Maximum
12 volt battery voltage [Battery]	10.0 V	-
Secondary SO2S (sensor 2) heater output duty	0.1 %	-
State of the engine	Running

[ ]: HDS Parameter

Malfunction Threshold

Either of the condition occurs:

The voltage level of the SO2HT terminal is OFF (high voltage) for at least 0.5 second despite the PCM outputs ON signal to the secondary HO2S (sensor 2).
The secondary HO2S (sensor 2) output driver in the PCM detects an over current for at least 0.5 second when the PCM outputs ON signal to the secondary HO2S (sensor 2).

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) SO2HT line short to power
Secondary HO2S (sensor 2) SO2HT line short to other line
PCM internal circuit failure

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.