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Reply To: PCM reflash question

Dave Tidman
Dave Tidman

Since the programs in the ECU are stored in non-volatile flash memory, I don’t think a re flash would help. If there was an issue, the ECM would usually throw a code that says something like ECU error.

P0420 is a catalyst efficiency code. Given the vehicle sat for a couple of years, I would tale a look at the upstream and downstream O2 sensors and do the other P0420 diagnostics. See this ETCG link: