P21A1 - Cylinder 6 Air-Fuel Ratio Imbalance

DTC DESCRIPTION P21A1 - CYLINDER 6 AIR-FUEL RATIO IMBALANCE

Description:	The air to fuel ratio imbalance torque monitor is designed to detect minimal differences in the air to fuel ratio between cylinders. This DTC sets when the minimal air to fuel ratio difference in cylinder 6 is greater than a calculated amount.
Possible Causes:	Leaking or contaminated cylinder 6 fuel injector External noise sources on the CKP circuit such as the charging circuit or aftermarket equipment Electrical noise on the CKP circuit from radio frequency interference or electro magnetic interference Low fuel pressure or running out of fuel Leaking EVAP purge valve Exhaust or intake air system leaks Exhaust gas recirculation (EGR) system Positive crankcase ventilation (PCV) system is leaking Incorrectly seated engine oil level indicator, tube or oil fill cap Base engine concerns
Diagnostic Aids:	This DTC may be caused by other systems related to cylinder 6. Diagnose any other cylinder 6 related DTCs first. The crankshaft position (CKP) sensor signal is very sensitive to electrical noise. Check the routing of the CKP sensor wiring harness.
Application	Key On Engine Off	Key On Engine Running	Continuous Memory
All	GO to Pinpoint Test H.