Subaru IMPREZA GD 2007 Series Manual page 1851

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Diagnostic Trouble Code (DTC) Detecting Criteria
GENERAL DESCRIPTION
AB:DTC P0133 O2 SENSOR CIRCUIT SLOW RESPONSE (BANK 1 SENSOR 1)
1. OUTLINE OF DIAGNOSIS
Detect the slow response of front oxygen (A/F) sensor.
Front oxygen (A/F) sensor cover has some ventilation holes for exhaust gas. Clogged ventilation holes are
diagnosed.
When the holes are clogged, the A/F output variation becomes slow comparing with the actual A/F variation
because oxygen which reaches the zirconia layer is insufficient. Therefore, if the sensor cover holes are
clogged, the rich to lean judgment in the ECM is delayed when the actual change from rich to lean occurs.
Judge as NG when the actual movement in comparison to the ECM control amount is slow.
(1)
(1) Cover
2. COMPONENT DESCRIPTION
(2)
(4)
(1) Atmosphere
(2) Exhaust gas
(3) ZrO
2
(4) Ceramic heater
(2)
(2) Zirconia
(3)
(1)
(2)
(A) Electromotive force
(B) Air fuel ratio
(C) Lean
(D) Rich
GD(H4DOTC)-60
(3) Clogging
(A)
(C) (B)
(3)
EN-01694
(D)
EN-01693