3.
Monitor "HO2S(B2S2)" parameter on scantool
Specification : 0.1 ~ 0.9V
Rear HO2S behind the catalytic conveter checks if purifying process performs well. purifying process is already done, the oxygen density of exhaust gas through catalytic converter is in the specified value.
Checking output signals from HO2S under detecting condition, if an output signal within the detecting condition lasts continuously, PCM sets P2272. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.
Item | Detecting Condition | Possible cause |
DTC Strategy | ● Determines if O2 sensor indicates lean exhaust while in Power Enrichment | ● Poor Connection ● Faulty HO2S ● Faulty PCM |
EnableConditions | ● Sensor not in cooled status ● Not in Transient Conditions status ● Airflow present ≥ 2 g/s ● Ignition voltage ≥ 10V ● Fuel reduction not active ● Engine running ● Engine running long enough ≥ 60sec. ● Power Enrichment conditions present ● Engine coolant warm enough ≥ 60℃( 140 °F) ● Above conditions met long enough ≥ 2.5sec. | |
Threshold value | ● O2 sensor voltage 〈 0.54V and, Air Fuel Ratio ≤ 13.5 | |
DiagnosisTime | ● Contineous (More than 11.25sec. failure for every 12.5sec. Test) | |
MIL On Condition | ● 2 Driving Cycles |
After warming-up, if accelerator pedal is released suddenly around 4000rpm, the HO2S signal reading will be lower than 200mV resulting from Fuel cut-off for the moment. Conversely, if suddenly accelerator pedal is depressed, HO2S signal reading will be around 0.6V ~1.0V. At idle, HO2S signal will switch from lean to rich normally.
A/F Ratio | Output Voltage(V) |
Rich | 0.75 ~ 1.00V |
Lean | 0 ~ 0.12V |
Connect scantool to DLC(Data Link Connector)
Warm up the engine to normal operating temperature.
Monitor "HO2S(B2S2)" parameter on scantool
Specification : 0.1 ~ 0.9V
Does the "HO2S(B2S2)" parameter operates correctly ?
▶Fault is intermittent caused by poor contact in Sensor’s and/or PCM’s connector or was repairedand PCM memory was not cleared. Thoroughly check connectors for looseness, poorconnection, bending, corrosion, contamination, deterioration, or damage. Repair or replaceas necessary and go to "Verification of Vehicle Repair" procedure
▶Go to "Component Inspection" procedure.
Visual Inspection
Visually check HO2S as follow.
Contamination, deformation or age of HO2S(B2/S2)
Is the HO2S(B2/S2) normal ?
▶ Go to "Check performance of HO2S" as follows.
▶ Substitute with a known-good HO2S(B2S2) and check for proper operation. If the problem is corrected,replace HO2S(B2S2) and then go to "Verification of Vehicle Repair" procedure.
Check performance of HO2S
Connect scantool to DLC(Data Link Connector)
Warm up the engine to normal operating temperature.
Monitor signal waveform of HO2S with scantool.
Specification : 0.1 ~ 0.9V.
Is the HO2S(B2S2) working properly ?
▶ Substitute with a known-good PCM and check for proper operation. If the problem is corrected,replace PCM and then go to "Verification of Vehicle Repair" procedure.
There is a memory reset function on scantool that can erase optional parts automaticallydetected and memorized by PCM.
▶ Substitute with a known-good HO2S(B2S2) and check for proper operation. If the problem is corrected,replace HO2S(B2S2) and then go to "Verification of Vehicle Repair" procedure.
After a repair, it is essential to verify that the fault has been corrected.
Monitor and record the Freeze Frame Data for the Diagnostic Trouble Code(DTC) which has been diagnosed.
Using a Scantool, Clear the DTCs
Operate the vehicle within conditions noted in the freeze frame data or enable conditions
Monitor that all rediness test have been verified as " Complete "
Are any DTCs present ?
▶ Go to the applicable troubleshoooting procedure.
▶ System is performing to specification at this time.
