CONVERTER EFFICIENCY CHARTS

Converters can only work efficiently if the engine is operating properly and the exhaust is leak tight. The charts at below show the typical relationship of engine exhaust, converter efficiency and resulting tailpipe emissions measured during emission tests. Both too- rich or too-lean conditions can cause emission failures.

HC CO NOx Possible Cause or Recommended Action
High
High
High
Replace converter and O2 sensor;
verify tune-up and correct any faults
High
Low
High
Replace converter, tune-up & check lean
AFR, leaking exhaust valves
Low
High
High
RReplace converter and O2 sensor
High
High
Low
Rich AFR, air injection
High
Low
Low
Run-in converter, tune-up, oil change
Low
Low
High
EGR, lean AFR, leaks, run-in converter,
use larger converter
Low
High
Low
O2 sensor, rich AFR

Low means less than the test fail point;
high means near or above the test fail point.





Converter Basics || Car Sound Quality || Why Converters Fail?
Oxygen Sensors || OBDII || Emission Code || EPA Policy
Converter Charts || Selecting Proper Universal
Certification || Warranty Info