Code 21 & 28 - Main O2 Sensor Circuit (SC300), Code 21 (Front Oxygen Sensor), Code 28 (Rear Oxygen Sensor)

WARNING: This page is about a different car, the 1995 Lexus SC 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 & 28 Flow Chart - 1 Of 2 (SC300) Code 21 - Front O2 Sensor - Code 28 Rear O2 Sensor

Fig 2: Code 21 & 28 Flow Chart - 2 Of 2 (SC300) Code 21 - Front O2 Sensor - Code 28 Rear O2 Sensor - Trouble Code Detection Driving Pattern Test