OBD-II Code · Emissions
P0422
Main Catalyst Efficiency Below Threshold (Bank 1)
medium severitySafe to drive$500-$2,000
Main cat efficiency low on bank 1.
Common symptoms
- CEL
Likely causes
- Failed main cat
- Misfires
Where to start
- Try the cheapest cause first. Start by checking: failed main cat.
- Cost & scope. $500-$2,000
- If the code returns after the fix: escalate to a shop or scanner with live-data and freeze-frame. A code that re-sets means the underlying fault is still there.
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