Result

Status AFS B1S1 or

O2S B2S2

A/F Condition and A/F Sensor Condition

Misfires

Suspected Trouble Areas

Proceed To

Lean/Rich

Lean/Rich

Normal

-

-

C

Lean

Lean

Actual air-fuel ratio lean

• PCV hose connections

• Injector blockage

• Gas leakage from exhaust system

• Air induction system

• Fuel pressure

• Engine Coolant Temperature (ECT) sensor

A

Rich

Rich

Actual air-fuel ratio rich

-

• Injector blockage or blockage

• Gas leakage from exhaust system

• Ignition system

• Fuel pressure

• ECT sensor

Lean

Lean/Rich

A/F sensor malfunction

-

• A/F sensor

B

Rich

Lean/Rich

A/F sensor malfunction

-

• A/F sensor

Lean: During A/F CONTROL, the A/F sensor output voltage (AFS) is consistently more than 3.35 V, and the HO2 sensor output voltage (O2S) is consistently less than 0.4 V.

Rich: During A/F CONTROL, the AFS is consistently less than 3.0 V, and the O2S is consistently more than 0.55 V. Lean/Rich: During A/F CONTROL of the ACTIVE TEST, the output voltage of the heated oxygen sensor alternates correctly.

Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

Don't pay hundreds of dollars to find out what is wrong with your car. This book is dedicated to helping the do it yourself home and independent technician understand and use OBD-II technology to diagnose and repair their own vehicles.

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