COMPONENT LOCATION
GENERAL DESCRIPTION

The normal operating temperature of the HO2S(Heated Oxygen Sensor) ranges from 350 to 850°C(662 to 1562°F). The HO2S heater greatly decreases the amount of time required for fuel control to become active. The ECM provides a pulse width modulated control circuit to adjust current through the heater. When the HO2S is cold, the value of the resistance is low and the current in the circuit is high. On the contrary, if the temperature in the resistor of the sensor rises, the current drops gradually.

DTC DESCRIPTION

If the PCM detects short to ground or open in heater under detecting conditions, PCM sets P0037. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.

DTC DETECTING CONDITION

Item

Detecting Condition

Possible cause

DTC Strategy

●

Detects a short to ground or open

●

Poor Connection

●

Open in Power Circuit

●

Open or short to ground in control circuit

●

HO2S(B1/S2)

●

PCM

Enable Conditions

●

No disabling Faults Present

●

Engine Running

●

11V ≤ Battery Voltage ≤ 16V

Threshold value

●

short to ground or open circuit

Diagnosis Time

●

Continuous

(More than 5 seconds failure for every 10 seconds test )

MIL On Condition

●

2 Driving Cycles

SIGNAL WAVEFORM AND DATA

The HO2S requires a minimum temperature to provide a closed loop fuel control system. So the HO2S contains a heater element to reduce its warm-up time and ensure its performance during all driving conditions. The PCM controls this heater element by duty cycle. The main relay supplies voltage to the heater and the PCM provides a ground circuit for activating the heater.

SPECIFICATION

Heater

Resistance (Ω)

3.0 ~ 4.0Ω [21℃(69.8℉)]

SCHEMATIC DIAGRAM
MONITOR DTC STATUS
1.

Check DTC Status

(1)

Connect scantool to Data Link Connector(DLC).

(2)

IG "ON".

(3)

Select "Diagnostic Trouble Codes(DTCs)" mode, and then Press F4(DTAL) to check DTC's information from the DTCs menu

(4)

Read "DTC Status" parameter.

(5)

Is parameter displayed "Present fault"?

▶ Go to "Terminal and connector inspection" procedure.

▶ Fault is intermittent caused by poor contact in the sensor’s and/or PCM’s connector or was repaired and PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, ending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.

TERMINAL AND CONNECTOR INSPECTION
1.

Many malfunctions in the electrical system are caused by poor harness and terminals.

Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.

2.

Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.

3.

Has a problem been found?

▶ Repair as necessary and go to "Verification of Vehicle Repair" procedure

▶ Go to " Power Circuit Inspection " procedure

POWER CIRCUIT INSPECTION
1.

IG "OFF" ＆ Disconnect HO2S(B1/S2) connector.

2.

IG "ON" ＆ ENG "OFF".

3.

Measure voltage between terminal 3 of HO2S(B1/S2) harness connector and chassis ground.

Specification : B+

4.

Is the measured voltage within specification ?

▶ Go to "Control Circuit Inspection" procedure.

▶ Repair open or short to ground in HO2S(B1/S2) Heater power circuit then, go to "Verification of Vehicle Repair" procedure.

CONTROL CIRCUIT INSPECTION
1.

Check short to ground in harness.

(1)

IG "OFF" and disconnect HO2S(B1/S2) connector.

(2)

Measure resistance between terminal 4 of HO2S(B1/S2) harness connector and chassis ground.

Specification : Infinite

(3)

Is the measured resistance within specification ?

▶ Go to "Check Open in harness" as follows.

▶ Repair short to ground in HO2S (B1/S2) heater control circuit and go to "Verification of Vehicle Repair" procedure.

2.

Check open in harness

(1)

IG "OFF" and disconnect HO2S(B1/S2) and PCM connector.

(2)

Measure resistance between terminal 4 of HO2S(B1/S2) harness connector and terminal 74 of PCM harness connector.

Specification : Approx. below 1Ω

(3)

Is the measured resistance within specification ?

▶ Go to "Component Inspection" procedure.

▶ Repair open in HO2S(B1/S2) heater control circuit and go to "Verifiction of Vehicle Repair" procedure.

COMPONENT INSPECTION
1.

Check HO2S(B1/S2) Heater resistance

(1)

IG "OFF" and disconnect HO2S(B1/S2) connector

(2)

Measure resistance between terminal 3 and 4 of HO2S(B1/S2)(Component Side)

Specification :

Heater

Resistance (Ω)

3.0 ~ 4.0 Ω at 21℃(69.8℉)

(3)

Is the measured resistance within specification ?

▶ Substitute with a known - good PCM and check for proper operation.

If the problem is corrected, go to "Verification of Vehicle Repair" procedure.

note

There is a memory reset function on scantool that can erase optional parts automatically detected and memorized by PCM.

Before or after testing PCM on the vehicle, use this function to reuse the PCM on the others.

▶ Substitute with a known - good HO2S(B1/S2) and check for proper operation.

If the problem is corrected, go to "Verification of Vehicle Repair" procedure.

VERIFICATION OF VEHICLE REPAIR

After a repair, it is essential to verify that the fault has been corrected.

1.

Connect scan tool and select "Diagnostic Trouble Codes(DTCs)" mode

2.

Press F4(DTAL) and confirm that "DTC Readiness Flag" indicates "Complete". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions

3.

Read "DTC Status" parameter

4.

Is parameter displayed "History(Not Present) fault"?

▶ System performing to specification at this time. Clear the DTC

▶ Go to the applicable troubleshooting procedure.

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