3.
Monitor "HO2S(B1S2)" parameter on scantool.
HO2S(B1/S2) is in the rear side of Catalytic Converter to check the proper operation of catalyst. Oxygen density after the catalytic converter has to be within specific range (around 0.5V when there is no acceclation and deceleration.)If the oxygen density changes in accordance with HO2S(B1/S1), it means the poor performance of catalytic converter.
If there is not any signal activity, ECM sets DTC P0140.
( This DTC might be caused by the malfunction of Heater circuit, so, check the heater circuit first. )
Item | Detecting Condition | Possible Cause |
DTC Strategy | ● No signal activity | ● Poor connection ● Open or short in signal circuit ● B1S2 ● ECM |
Enable Conditions | ● Time after dew point is reached ＞ 10 sec | |
Threshold Value | ● Signal voltage changes more than 2V after HO2S heater operation stops ＞ 4 times | |
MIL ON Condition | ● 3 driving cycle |
※ B1S1 : upstream oxygen sensor / B1S2 : downstream oxygen sensor
A/F Ratio | Output Voltage (V) |
Rich | 0.6 ~ 1.0V |
Lean | 0 ~ 0.4V |
Connect scantool to DLC (Data Link Cable).
Warm up the engine to normal operating temperature.
Monitor "HO2S(B1S2)" parameter on scantool.
Is the "HO2S(B1S2)" parameter displayed correctly?
▶Fault is intermittent caused by poor contact in the sensor’s and/or ECM’s connector or was repaired and ECM memory was not cleared. Thoroughly check connectors for looseness, poorconnection, ending, corrosion, contamination, deterioration, or damage. Repair or replace asnecessary and go to "Verification of Vehicle Repair" procedure.
▶ Go to "Terminal and Connector Inspection" procedure.
This DTC might be caused by the malfunction of Heater circuit, so, check the heater circuit first.
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.
Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
Has a problem been found?
▶ Repair as necessary and go to "Verification of vehicle Repair" procedure.
▶ Go to " Signal Circuit Inspection " procedure.
IG "OFF".
Disconnect HO2S(B1/S2) connector.
IG "ON" ＆ ENG "OFF".
Measure voltage between terminal 1 of HO2S(B1/S2) and chassis ground.
Specification : Approx. 0.45V
Is the measured voltage within specification?
▶ Go to "Component Inspection" procedure.
▶ Repair or replace as necessary and then, go to "Verification of Vehicle Repair"procedure.
Visual Inspection.
IG "OFF"
Disconnect HO2S(B1/S2) connector.
Check that HO2S(B1S2) is contaminated or damaged by foreign materials.
Has a problem been found?
▶ Go to "Check ECM" as follows.
▶ Substitute with a known - good HO2S(B1/S2) and check for proper operation.
▶ If the problem is corrected, replace HO2S(B1/S2) and go to "Verification of Vehicle Repair" procedure.
Check ECM.
IG "OFF" and disconnect B1S2 connector.
Connect scantool and Key "ON".
Select simulation function on scantool.
Simulate voltage at terminal 1 of HO2S(B1/S2) signal connector.
Does the signal value of HO2S(B1/S2) change according to simulation voltage?
▶ Thoroughly check connectors for looseness, poor connection, bending, corrosion,contamination, deterioration, or damage. Repair or replace as necessary and go to "Verificationof Vehicle Repair" procedure.
▶ Substitute with a known - good ECM and check for proper operation.
▶ If the problem is corrected, replace ECM and go to "Verification of Vehicle Repair" procedure.
After a repair, it is essential to verify that the fault has been corrected.
Connect scan tool and select "Diagnostic Trouble Codes(DTCs)" mode.
Clear the DTCs and Operate the vehicle within DTC Enable conditions in General information.
Are any DTCs present ?
▶ Go to the applicable troubleshooting procedure.
▶ System is performing to specification at this time.
