The HO2S(Heated Oxygen Sensor) is used to supply the PCM with information regarding the composition of the air/fuel mixture. The HO2S is positioned in the exhaust pipe ahead of the TWC. To measure the oxygen content, the HO2S requires a supply of ambient air as a reference. Since this is supplied through the wiring, the lead must not be clamped or damaged in any other way. The HO2S produces a voltage that varies between 0.1V and 0.9V under normal operating conditions. The Engine Control Module (PCM) monitors this voltage and determines if the exhaust gas is lean or rich. If the voltage input at the PCM is under approx. 0.45V the exhaust is lean, and if the voltage input is over approx. 0.45V the exhaust is rich. The PCM constantly monitors the HO2S signal during closed loop operation and compensates for a rich or lean condition by decreasing or increasing injector pulse width as necessary.
The linear O2 sensor is mounted on the front side of the Catalytic Converter (warm-up catalytic converter) or in the front exhaust pipe. It detects a wide range of air/fuel ratios in the exhaust gas from the rich to lean regions. This linear O2 sensor produces a current that corresponds to a specific air/fuel ratio. The PCM monitors this signal and determines whether the air/fuel mixture is rich or lean. The PCM constantly monitors the linear O2 sensor and increases or decreases the fuel injection duration using this signal. This is called closed-loop fuel control operation.
PCM sets DTC P0131 if the HO2S(B1S1) voltage remains excessively low for a predetermined time.
The control unit of the linear oxygen sensor built inside the PCM monitors short circuit error on all front Heated Oxygen Sensor (HO2S) control lines (VRC, VIP, VG, VN) and PCM sets P0131 with short circuit to ground.
If same code is set again in the next driving cycle, MIL is illuminated.
Item | Detecting Condition | Possible Cause |
DTC Strategy |
•
Voltage range check | 1. Short to ground in signal harness 2. Poor connection or damaged harness 3. Faulty Heated O2 Sensor(HO2S) |
Enable Conditions |
•
Lambda close loop activated
•
Lambda controller on max. limit during 10 sec.
•
Canister purge valve closed
•
No relevant failure
•
10V< Battery voltage <16V | |
Threshold Value |
•
HO2S(B1S1) < 0.02V | |
Diagnostic Time |
•
60 sec. | |
Mil On Condition |
•
2 Driving Cycles |
Item | Detecting Condition | Possible Cause |
DTC Strategy |
•
Electrical check | 1. Short to ground in signal harness 2. Poor connection or damaged harness 3. Faulty Heated O2 Sensor(HO2S) |
Enable Conditions |
•
10V < Battery voltage < 16V
•
Ignition key On | |
Threshold Value |
•
Error bit information from HW circuit | |
Diagnostic Time |
•
0.5 sec. | |
Mil On Condition |
•
2 Driving Cycles |
BINARY
LINEAR
Test Condition | GDS Parameter | ||
O2 SNSR VOL.-B1/S1 | O2 SNSR VOL.-B1/S2 | ||
Normal Value when circuit is normal | Idle after warm up | Signal is switching from rich(above 0.45V) to lean(below 0.45V) a minimum of 3 times in 10 seconds. | above 0.7V |
HO2S(B1S1) signal circuit open | Approx. 0.43~0.45V | - | |
HO2S(B1S2) signal circuit open | - | Approx. 0.43~0.45V | |
1. Normal value with idle after warm up : Signal is switching from rich(above 0.45V) to lean(below 0.45V) a minimum of 3 times in 10 seconds.
2. GDS display with open in signal circuit : Approx. 0.43~0.45V
