What is OBD?

Emission Monitoring System

Where is OBD located?

In the PCM

What does OBD do?

Monitor emission systems as mandated by EPA and CARB

How is a customer notified of an emission failure?

MIL (Malfunction Indicator Lamp)

When did OBD I start?

1988 California Vehicles

When did OBD II start?

1996 (Phase in since 1994)

What systems are monitored by OBD I?

HO2S

EGR

Fuel

Input Sensors

What systems are NOT monitored by OBD I?

HO2S HO2S HeaterEGRCatalyst EfficiencyMisfireSecondary AirEVAP systemTSTATPCV

When does OBD I turn on the MIL?

When the fault is present

When the fault is not present

When does OBD I turn off the MIL?

What systems are monitored by OBD II?

HO2S HO2S HeaterEGRFuel SystemComprehensive Component (CCM)Catalyst EfficiencyMisfireEVAP systemSecondary Air SystemTSTATPCV

Which OBD II monitors are continuous?

HO2S HO2S HeaterEGRFuel System Comprehensive Component (CCM)Catalyst EfficiencyMisfire EVAP systemSecondary Air SystemTSTATPCV

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When does OBD II turn off the MIL?

3 consecutive trips without the fault occuring

3 consecutive trips without the fault occuring in ‘similar conditions window’ for misfire & fuel system faults

What turns on the MIL?

When does the MIL turn on?

MIL may illuminate on second consecutive occurrence (type B fault)

MIL may illuminate at first occurrence (type A fault)

How are DTCs Cleared?

With a scan tool (preferred)

Disconnect battery (not preferred)

DTC is erased after 40 warm up cycles without fault present

Up to 80 warm up cycles for misfire or fuel system faults

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