The Air Fuel Ratio AF sensor has an output delay of a few seconds and the Heated Oxygen HO sensor has a maximum output delay of approximately seconds

Case

A/F Sensor (Sensor 1) Output Voltage

HO2 Sensor (Sensor 2) Output Voltage

Main Suspected Trouble Areas

Injection volume +25 % -12.5 %

♦ _TLJ-

Injection volume +25 % -12.5 %

♦ _TLJ-

1

Output voltage More than 3.35 V Less than 3.0 V

-U-125

Output voltage More than 0.55 V Less than 0.4 V

^TK

Injection volume +25 % -12.5 %

♦ _TLJ-

Injection volume +25 % -12.5 %

♦ _TLJ-

• A/F sensor circuit

2

Output voltage Almost no reaction

-NG

Output voltage More than 0.55 V Less than 0.4 V

3

Injection volume +25 % -12.5 %

f^FLJ-

Injection volume +25 % -12.5 %

• HO2 sensor heater

• HO2 sensor circuit

Output voltage More than 3.35 V Less than 3.0 V

-U-125

Output voltage Almost no reaction

-NG

4

Injection volume +25 % -12.5 %

Injection volume +25 % -12.5 %

• Fuel pressure

• Gas leakage from

Output voltage Almost

MP

Output voltage Almost

MP

exhaust system (Air-fuel ratio extremely lean or rich)

no reaction

no reaction

• Following the A/F CONTROL procedure enables technicians to check and graph the voltage outputs of both the A/F and HO2 sensors.

• To display the graph, select the following menu items on the tester: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL / USER DATA / AFS B1S1 and O2S B1S2 or AFS B2S1 and O2S B2S2, and press the YES button and then the ENTER button followed by the F4 button.

HINT:

Read freeze frame data using an intelligent tester. Freeze frame data record the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data, from the time the malfunction occurred.

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