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173 Posts
Discussion Starter · #1 ·
I keep throwing a CEL, 0420 Catalytic below threshold, and was wondering if anyone might know what is causing it. I'm assuming its the rear O2 sensor (post0cat) but don't know exactly how to interpret that.

I recently installed the BR stage 1-2 with the high flow cat and flash about 2 weeks ago but had the CEL 2 times this weekend( I checked it and cleared it with my datalogger if your wondering).

If anyone has any ideas why its doing this the help would be appreciated.

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