Wondering if any Saturn techs still here that might have some ideas about a P0420 low catalytic converter efficiency.
Thanks.
Jul 17, 2018 at 1:15 PM
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ASEMASTER6371
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52,796 POSTS
Good evening.
The 420 is a code for the catatlytic converter. it needs to be replaced.
The precious metals inside are worn out and the downstream O2 sensor is reading the same as the upstream. The downstream O2 sensor should be a steady reading, not varying.