The HO2S 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.
PCM sets DTC P0130 if the PCM detects that the front HO2S signal circuit is open.
ITEM
DETECTING CONDITION
POSSIBL ECAUSE
DTC Strategy
? Voltage range check
? Open in signal harness.
? Open in ground harness.
? Contact resistance in connectors.
? Faulty Heated O2 Sensor(HO2S).
Enable Condition
? Sensor preheating and full heating phases finished
? Modelled exhausr gas temp, > 600°C(1112°F)
? Lambda control active
? No relevant failure
? Battery voltage >10V
Case1)
Threshold Value
? Lambda control not active within the defined time
Case2)
? 0,49V > Down HO2S > 0,37V and sensor element resistance > 60 KO
Diagnostic Time
? 30~100 sec. depending on start temp.
? 10 sec.