On Board Diagnosis Logic

To judge the malfunction of air fuel ratio (A/F) sensor 1, this diagnosis measures response time of the A/F signal computed by ECM from the air fuel ratio (A/F) sensor 1 signal. The time is compensated by engine operating (speed and load), fuel feedback control constant, and the air fuel ratio (A/F) sensor 1 temperature index. Judgment is based on whether the compensated time (the A/F sensor 1 signal cycling time index) is inordinately long or not.

DTC DETECTING CONDITION REFERENCE CHART

DTC No.	Trouble diagnosis name	DTC detecting condition	Possible Cause
P0133 0133	Air fuel ratio (A/F) sensor 1 circuit slow response	The response of the A/F signal computed by ECM from A/F sensor 1 signal takes more than the specified time.	Harness or connectors [Air fuel ratio (A/F) sensor circuit is open or shorted.] Air fuel ratio (A/F) sensor 1 Air fuel ratio (A/F) sensor heater 1 Fuel pressure Fuel injector Intake air leaks Exhaust gas leaks PCV Mass air flow sensor