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.

Checking current from HO2S under detecting condition,if the heater current is below a certain threshold for more than predeterminate time, PCM sets P0030. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.

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.

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.

3.

Has a problem been found?

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

▶ Go to " Component Inspection " procedure.

1.

Check HO2S(B1/S1) Heater resistance

(1)

IG "OFF" and disconnect HO2S(B1/S1) connector

(2)

Measure resistance between terminal 3 and 4 of HO2S(B1/S1)(Component Side)

Specification : 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 automaticallydetected 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/S1) and check for proper operation.

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

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

4.

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

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

▶ Go to the applicable troubleshooting procedure.