2.
Probe(+) : O2 sensor harness connector NO3.
Probe(-) : Chassis ground.
The ECM determines front HO2S heater fault and sets DTC P0030 if the front HO2S heater control driver inside the ECM fails or HO2S is not operational after an elapse of predetermined time since engine start or front HO2S tip temperature is out of normal working range. The ECM illuminates the MIL on the second consecutive driving cycle that the diagnostic runs and fails.
The ECM sets DTC P0038 if the ECM detects that the rear HO2S heater control line is open or short to battery line.
Item | Detecting Condition | Possible cause |
Monitoring Strategy | ● Signal check, high | - Short HO2S heater to battery - Faulty HO2S heater - Faulty ECM |
Threshold value | ● Heater voltage > 3.6V | |
Enable Conditions | ● Heater control Disable | |
Diagnostic Time | ● Continuous | |
MIL on condition | ● 2 driving cycle |
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.
Service standard
Front O2 sensor heater resistance : 80℃(176℉) 8.0~14.0Ω
Rear O2 sensor heater resistance : 80℃176℉) 8.0~14.0Ω
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 "Visual inspection" procedure.
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.
