P0420

Support for Lotus Elise, Exige and Exige S
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hackish
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P0420

Post by hackish » Mon Sep 24, 2012 7:22 pm

P0420 on a Lotus... aka Cat Efficiency Below threshold... The factory computer monitors the differences between the front and rear O2 sensors and if they don't follow a pre-defined pattern the factory computer decides that the cat is not working well enough to satisfy the emissions (smog) limits. The check engine light will be illuminated and the vehicle definitely won't pass any smog tests.

Ultimately to be an environmentally responsible individual it may be best to replace the cat with a high quality unit. Personally I prefer the stainless core cats manufactured by Random Technologies as they do not offer a significant amount of backpressure or performance loss and are still very successful at passing tailpipe smog tests.

Some Lotus owners do not drive their vehicles on the street and these emissions checks are merely an annoyance.

These are the stock 2006 Exige settings.
emissions.jpg
These are the stock settings that affect the P0420 emissions code.
emissions.jpg (45.25 KiB) Viewed 9126 times
Here are the recommended settings to disable the code.
emissions2.jpg
These settings will disable the P0420 check.
emissions2.jpg (44.59 KiB) Viewed 9126 times
This will leave the emissions monitors as incomplete.

-Michael

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