LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Dodge and Ram >> 1987 >> Charger Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> 4-CYL EFI System >> Testing >> Trouble Codes >> Code 21
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Code 21

Problem with O2 Sensor feedback circuit. Occurs if engine is in closed loop, but O2 sensor stays rich or lean (no signal) for more than 22 seconds. Engine temperature should be above 170°F (77°C) and engine speed is above 2000 RPM.