DTC 21

Fig. 9 Diagnostic Code 21 (Main Oxygen Sensor & Heater Signal, Part 1 Of 4):

Fig. 9 Diagnostic Code 21 (Main Oxygen Sensor & Heater Signal, Part 2 Of 4):

Fig. 9 Diagnostic Code 21 (Main Oxygen Sensor & Heater Signal, Part 3 Of 4):

Fig. 9 Diagnostic Code 21 (Main Oxygen Sensor & Heater Signal, Part 4 Of 4):