Code 21 - Main O2 Sensor CKT (GS300 CALIF. - Front O2 Sensor)

WARNING: This page is about a different car, the 1995 Lexus GS 300. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: After repairs are completed, perform TROUBLE CODE DETECTION DRIVING PATTERN TEST.

Fig 1: Code 21 Flow Chart - 1 Of 2 (GS300 Calif.) Code 21 - Main O2 Sensor Circuit (Front O2 Sensor)

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Fig 2: Code 21 Flow Chart - 2 Of 2 (GS300 Calif.) Code 21 - Main O2 Sensor Circuit (Front O2 Sensor)

Fig 3: Code 21 Trouble Code Detection Test (GS300 Calif.) Code 21 - Main O2 Sensor Circuit (Front O2 Sensor)