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Lambda & Catalytic Converter Efficiency
CO2 @ 25 mph O2 @ 25 mph HC @ 25 mph
CO @ 25 mph NOx @ 25 mph
Results: Lambda Results: CAT Efficiency

This DCF compensated Lambda calculator is accurate and designed for use with Smog Check VIR printouts.
However, the catalyst efficiency calculation is only approximate and will not be accurate if there are exhaust leaks or air injection downstream.
Also be aware that catalyst inefficiency can be a result of vehicle fuel control issues, etc., and not necessarily catalyst degradation.