The only TSB i've seen here around is the one from Subaru. But someone said that it was taken down and revised?

Thread revival...

I just installed an AEM wideband and removed the O2 sensor downstream of the cat in order to prep for FI. Of course the CEL came on but consequently noticed that cruise control doesn’t work anymore.

Does a CEL really disable cruise control??


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yes

Well yes and no. Depends on what the CEL is for.

Any idea as to the reasoning and logic behind disabling cruise control when there’s a catalyst inefficiency?


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It thinks the inefficacy is a failure of the system and is trying to protect the engine from damage. The system doesn't know why the issue occurred it just knows it did.
Pretty much any CEL that could cause damage triggers what is nicknamed "limp mode".

@kimcheefists
This. It's a liability issue for toyota and subaru for the P0420 codes and other catalyst codes. Because your AFR data reads "incorrect'" now and the pre cat and post cat O2 data is also "incorrect" letting cruise control run would be dangerous, it could very well go full throttle and lean the car out, or make its acceleration choppy and sporadic in an effort to counter the engine issue. Making a cruise control system that takes into account engine codes and does a limp home cruise control type deal would be very difficult and also defeat the purpose of being efficient.

This is why your tuner will disable the P0420 code when you finish the FI install, or when others install things like a header.