2GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
ES–355
ES
• If a A/F sensor malfunction is detected, the ECM sets a DTC.
MONITOR DESCRIPTION
Sensor voltage detection monitor
Under the air-fuel ratio feedback control, if the A/F sensor output voltage indicates rich or lean for a certain
period of time, the ECM determines that there is a malfunction in the A/F sensor. The ECM illuminates the
MIL and sets a DTC.
Example:
(1)If the A/F sensor voltage output is less than 2.8 V (very rich condition) for 10 seconds, despite the
HO2 sensor output voltage being less than 0.6 V, the ECM sets DTC P2196. Alternatively, if the A/F
sensor output voltage is more than 3.8 V (very lean condition) for 15 seconds, despite the HO2
sensor output voltage being 0.15 V or more, DTC P2195 is set.
(2)Sensor current detection monitor
(3)A rich air-fuel mixture causes a low A/F sensor current, and a lean air-fuel mixture causes a high A/
F sensor current. Therefore, the sensor output becomes low during acceleration, and it becomes
high during deceleration with the throttle valve fully closed. The ECM monitors the A/F sensor
current during fuel-cut and detects any abnormal current values.
(4)If the A/F sensor output is 3.6 mA or more for more than 3 seconds of cumulative time, the ECM
interprets this as a malfunction in the A/F sensor and sets DTC P2195 (high-side stuck). If the A/F
sensor output is 1.0 mA or less for more than 3 seconds of cumulative time, the ECM sets DTC
P2196 (low-side stuck).
MONITOR STRATEGY
Related DTCs
P2195: A/F sensor (Bank 1) signal stuck lean
P2196: A/F sensor (Bank 1) signal stuck rich
P2197: A/F sensor (Bank 2) signal stuck lean
P2198: A/F sensor (Bank 2) signal stuck rich
Air Fuel Ratio Sensor Current Monitor
Cumulative Time "t" = t1 + t2 =3 seconds or more
Fuel-Cut
ON
OFF
Delay (3 seconds) Delay (3 seconds) Delay (3 seconds)
3 seconds or more
Normal Sensor Output Abnormal Sensor Output Time
Sensor Current (mA)
High Side Threshold
Low Side Threshold
t1 t2
A107165E05
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