[f30Seth]

I tried searching with "CEL" but no direct answers to my questions from the result.

1.Do installing CATLESS DP always throw CEL?

or is it a hit or miss?

2. If I wanted to be foolproof, which tool or procedure do I have to buy/undergo with the purchase of ER DP? I read somewhere that there is a DP FIX or something?

3. Does installing and taking off my piggyback leave any log in the car's system? I really need a frank answer to this if yes, why is there a tool for clearing codes on sale?

I have a N26 328i with BMS stage 1 running. Luckily, it seems installing DP doesn't void warranty where I live, but I'm afraid throwing CEL might cause them to run a diagnostic tool.

[utenigma]

Originally Posted by f30Seth

I tried searching with "CEL" but no direct answers to my questions from the result.

1.Do installing CATLESS DP always throw CEL?

or is it a hit or miss?

2. If I wanted to be foolproof, which tool or procedure do I have to buy/undergo with the purchase of ER DP? I read somewhere that there is a DP FIX or something?

3. Does installing and taking off my piggyback leave any log in the car's system? I really need a frank answer to this if yes, why is there a tool for clearing codes on sale?

I have a N26 328i with BMS stage 1 running. Luckily, it seems installing DP doesn't void warranty where I live, but I'm afraid throwing CEL might cause them to run a diagnostic tool.

Yes, a catless downpipe will always throw a check engine light. The secondary o2 sensor behind the cat's primary purpose is for emissions regulation reporting - it verifies that the cat is doing it's job of converting CO to CO2 and partially burnt fuel to CO2 and water.

If your car has no cat, this will not occur and the secondary o2 sensor will tell the tale throwing a CEL

The BMS stage 2 will auto-clear the CEL caused by a catless-downpipe. The stage 2 can also read and clear codes in the DME which you can do before service.

I'm taking my car in for service next week (BMS stage 2 + ER Catless downpipe). I put the OEM cat back on last night and will run it through the weekend on map 0 (stock) then clear the codes and remove the tune prior to bringing it in.

[rmsurfer212]

As far as emissions are concerned, what are the options for keeping the CEL off and allowing the car to properly cycle before bringing it in? I know that the BMS stage 2 will auto-clear the codes, but won't allow you to pass emissions. I bought the DP fix from evolution racewerks, but it never worked. Just curious to see what others are doing to circumvent this problem. Thanks.

[utenigma]

For emissions testing put the cat back in then let the car go through 3 heat cycles (full hot to full cold). This will throw the all good flag for emissions

As a rule I put the cat in then drive it for a week before taking it in for inspection

[f30Seth]

Originally Posted by utenigma

For emissions testing put the cat back in then let the car go through 3 heat cycles (full hot to full cold). This will throw the all good flag for emissions

As a rule I put the cat in then drive it for a week before taking it in for inspection

Thanks for your detailed clarifying answer. That helps me a quite bit.
So to go CATLESS DP, it's either stage 2 or don't do it at all for me.

I really wish I have a garage to do the installation myself.
How long does reverting back to stock take for you usually?

[rmsurfer212]

Originally Posted by utenigma

For emissions testing put the cat back in then let the car go through 3 heat cycles (full hot to full cold). This will throw the all good flag for emissions

As a rule I put the cat in then drive it for a week before taking it in for inspection

thanks I will try that

[utenigma]

Originally Posted by f30Seth

Thanks for your detailed clarifying answer. That helps me a quite bit.
So to go CATLESS DP, it's either stage 2 or don't do it at all for me.

I really wish I have a garage to do the installation myself.
How long does reverting back to stock take for you usually?

I did it on Wednesday for the first time (first time putting the cat back on) and I happened to time it. On the floor of my garage with the front of the car on Rhino ramps it took me 2:30 - most of that time was me crawling under the car, forgetting something, crawling out from under the car etc.

If I had access to a lift it would have been less than an hour.

When I installed the catless it took me like 4 hours - I expect putting it back in after the dealer trip to be closer to an hour. Practice makes perfect