OBD
P21A2
Cylinder 7 Air-Fuel Ratio Imbalance
What it means
P21A2 means Cylinder 7 Air-Fuel Ratio Imbalance.
Check these first
- A weak or contaminated oxygen sensor
- A dirty or clogged fuel injector on cylinder 7
- A dirty mass airflow sensor
- An intake manifold leak
- Low compression on cylinder 7
What to do next
- Read the cylinder 7 fuel trim on a scan tool
- Swap the cylinder 7 injector and see if the fault follows
- Check the oxygen sensor signal
- Clean the mass airflow sensor
- Run a compression test on cylinder 7
- Clear the code and retest
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Updated
Generic SAE J2012 definition. Last updated 2026-10-10.