4.
Check for HO2S signal at idle.
caution
The data shown above is only for reference and there may be a little difference actually.
This is the inspection procedure to determine whether it is present DTC or memoried one by monitoring the current signal or by using the function of oscilloscope with Hi-scan pro.
Connect scan tool to DLC.
IG KEY : ON
Start engine and warm up to operating temperature.
Check for HO2S signal at idle.
The data shown above is only for reference and there may be a little difference actually.
Service standard
Front O2 sensor heater resistance : 80℃(176℉) 8.0~14.0Ω
Rear O2 sensor heater resistance : 80℃(176℉) 8.0~14.0Ω
Service standard
Front O2 sensor heater wire connected : Connected.
Front O2 sensor heater wire disconnected : Disconnected.
Rear O2 sensor heater wire connected : Connected.
Rear O2 sensor heater wire disconnected : Disconnected.
This inspection procedure is recommended when service data with scan tool is not enough.
Idle RPM
Probe(+) : O2 sensor harness connector NO3.
Probe(-) : Chassis ground.
This figure shows the waveform measured at terminal 3 of HO2S.
Point ① is the duration heater operates and the normal voltage is below 0.8V.
In case the output voltage is over 0.8V.
Possible cause:Poor ECM ground connection Or poor ECM connector’s connection
Point ② is the duration heater doesn’t operates and the normal voltage is battery voltage.
This figure shows the waveform measured at terminal 3 of HO2S.
Point ① is the duration heater operates and the normal voltage is below 0.8V.
In case the output voltage is over 0.8V.
Possible cause:Poor ECM ground connection Or poor ECM connector’s connection
Point ② is the duration heater doesn’t operates and the normal voltage is battery voltage.
If heater control duty ratio is changed,when inspecting heater wire and signal waveform while open loop condition with scan tool,the heater control works normally.
In case there is no symptom and wrong data but DTC is shown
The problem may be intermittent so slightly shake the connector and harness vertically and horizontally to check if there is any data changes
If the data changes normally, the problem was intermittent so erase DTC and verify the same DTC reoccure.
Go to "Terminal and Connector inspection" procedure.
In case there is symptom and wrong data with DTC
Check open,short or connector’s connection for HO2S.
Check the deterioration of HO2S performance.
Go to "Circuit Inspection" procedure.
