engine code P0420
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engine code P0420
Hello,
I have a 99 es 300 with 68000 miles on it. CEL and trac off light are both on and getting a P0420 code bank 1. Does anyone know what this problem most likely is ?/
I have a 99 es 300 with 68000 miles on it. CEL and trac off light are both on and getting a P0420 code bank 1. Does anyone know what this problem most likely is ?/
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the P0420 code means "catalyst system efficiency below threshold." The two upstream sensors do not measure catalyst performance, so diagnosis should start with the downstream sensor after the catalyst, as Phoenix said.
Last edited by intrmsof2; 03-17-06 at 10:44 AM. Reason: misstatement
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