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Discussion Starter #1
Okay so I’ve had my RS for about 5 months, it’s full bolt ons with a catless downpipe and tuned on an accessport by a local tuner. My o2 sensor and o2 sensor heater monitors won’t set even after I gave it to a performance shop to figure out for a month, this shop usually works on subies and Evo’s with some experience with an RS but no luck setting the monitors. I bought the car with the full bolt ons and maybe the emissions system was tampered with by the previous owner to remove CEL? Idk but I can’t really think of anything else besides going stock DP and stock tune, although I’ve seen this doesn’t solve it for some people with this issue while it does solve it for others. The car was is a rebuilt title if that could change anything. Any help/advice is appreciated, thank you.
 

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If the car has no cat, the tuner can hide the CEL in the dashboard and disable readiness monitors. If you're tuned via a Cobb AP, flash one of Cobb's OTS maps and drive for a few miles to see if the CEL comes on to confirm that your O2 sensors are still working.
 

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I’m sorry I’m not exactly sure what you’re trying to do. Your tuner can hide the p0420 CEL but it will not hide the actual fault in the computer and it will still trip any smog/emissions testing

explain what you mean when you keeping saying “set”. Set what
 

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@Hank to the rescue:

If on the stock turbo, having either an exhaust or DP does the same thing. You don't need both, so depending on the state you may want to put the stock DP in so you don't have to worry about emissions.
 

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Discussion Starter #5
@Hank to the rescue:

If on the stock turbo, having either an exhaust or DP does the same thing. You don't need both, so depending on the state you may want to put the stock DP in so you don't have to worry about emissions.
Looks like that’s what I need, should I assume this will set the o2 sensor heater monitor then too?
 

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Check to see what plugs you have. I couldnt ready the monitors with colder than stock range plugs
 

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…...My o2 sensor and o2 sensor heater monitors won’t set ….
The issue is in the tune settings for sure. If you map isn't "locked" by the previous tuner I can fix it for you, but I'll need your map file. That said, if your tuner can't correct the problem, then you definitely need a new tuner.

The issue is that the tuner likely disabled the OBD code for Cat Efficiency (P0420) because that is easier than setting the parameters for the downstream O2 sensor so that it will still "work", but only in a very limited range.
 

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Discussion Starter #10
The issue is in the tune settings for sure. If you map isn't "locked" by the previous tuner I can fix it for you, but I'll need your map file. That said, if your tuner can't correct the problem, then you definitely need a new tuner.

The issue is that the tuner likely disabled the OBD code for Cat Efficiency (P0420) because that is easier than setting the parameters for the downstream O2 sensor so that it will still "work", but only in a very limited range.
Okay I called my tuner and he said that he did in fact disable that code and that I can bring it back so he can turn it on again(once I get my car back from the dealership). I bought the defouler for the o2 sensor that hank suggested above and should be coming in soon too so I think both the tune and defouler should fix it. I’ll keep you posted. I appreciate everyone’s help
 

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Make sure you save that to another tune slot so you can easily switch between the tunes when it's emissions time.
 

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In the event that the vehicle has no feline, the tuner can conceal the CEL in the dashboard and impair status screens. In case you're tuned by means of Tutuapp 9apps Showbox a Cobb AP, streak one of Cobb's OTS guides and travel for a couple of miles to check whether the CEL makes advances on affirm that your O2 sensors are as yet working.
 
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