Component Location
General Description
In order to control emissions of the CO, HC and NOx components of the exhaust gas, heated oxygen sensor (HO2S), mounted on the front side and rear side of catalytic converter, detects the oxygen content in the exhaust gas. The front HO2S signal is used to control air/fuel ratio (closed loop fuel control) and the rear HO2S signal is used to monitor front HO2S and catalyst for proper operation. The HO2S requires a minimum temperature to operate properly and provide a closed loop fuel control system. The HO2S contains the heater element to reduce its warming-up time and ensure its performance during all driving conditions. The oxygen sensor generates a voltage that indicates the difference between the oxygen content of the exhaust stream and the oxygen content of ambient air. When the exhaust stream is “rich,” there is more oxygen in the ambient air than in the exhaust stream, so the voltage will be higher.
DTC Description
Checking output signals from HO2S under detecting condition, if ECM judges it's signals too slow, ECM sets P0153.
DTC Detecting Condition
Item | Detecting Condition | Possible Cause |
DTC Strategy | Monitor HO2S's response rate
| Poor connection
B2S1
ECM
|
Enable Conditions | 1240 < rpm < 2000
30% < Engine load < 63%
EGT around upstream O2S > 400C
|
Threshold value | Average cycle period of O2S signal for 7 cycles > 2.3sec or < 0.2 sec
|
Diagnosis Time | -
|
MIL On Condition | NO MIL
|
Diagnostic Circuit Diagram
Signal Waveform & Data
Fig.1) The signal waveforms of front HO2S(the lower) and heater(the upper) at idle
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, Normally HO2S signal will switch from lean to rich with 3 Hz. And as racing, Its frequency rises.