Installed Catalytic Converter backwards

Not to the engine but the emissions system might not work properly. Some converters have two or three different stages the unburned fuel goes through and it must pass through them in a specific order. Beginning with '96 models, there will be an oxygen sensor after the converter. The Engine Computer compares the switching rate from lean to centered to rich between the two sensors, (before and after the converter). When the second one begins switching just as fast as the front one, the computer knows nothing is taking place in the converter and it will turn on the Check Engine light and set the appropriate diagnostic fault code related to converter efficiency. If your Check Engine light does not turn on, chances are you have a single-stage converter and it will work ok.

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