[squixs]

Hi all,

Last week I bought a used HJS 300 Cell EUR6 downpipe which was used for around 5k miles. Soon after that, a bmw specialized tuner shop installed the downpipe for me.

Because I was about to flash my car with BM3 Stage 1, I hooked up my car to the Bootmod3 app, read codes and saw this:

180001 Catalyst: Efficiency Below Threshold

The next day a CEL light was displayed in the dash...
I cleared codes and just checked for DME errors again using BM3 and the same error entry is back.

From what I had understand, the HJS 300 Euro6 cat is supposed to not trigger CEL lights, right? Could this be an installation error or something?

Thanks in advance!

[McPurrs]

You would hear an exhaust leak if it were installed wrong. Not sure the O2s reach the wrong holes...

[Anthony1s]

So, there was a post a while back where Fabspeed admitted that their downpipes do give CEL's ("*to a small percentage of cars" in their words) and corrected their statement to be "100% guaranteed to not cause a LASTING check engine light"

The solution being to run the car with the CEL for a certain amount of time/mileage then the check engine light will go away as the car adapts. But if you keep clearing the light, the ECUs won't know to adapt, so the light will keep coming on.

I know you don't have a Fabspeed downpipe, but maybe that solution will help you too... Don't clear the CEL and drive around for a few weeks.

[XutvJet]

Been running my HJS 300 cell DP for 2 months and 1500 miles now without a code. Given that the code was thrown shortly after install would make me start looking at the O2 sensors or a leak at the DP and turbo connection. You really should replace the gasket at this junction.

Lastly, are you sure you were sold an HJS 300 cell DP?

[squixs]

They replaced gaskets. DP part nr checks out

[ddk632]

Bizarre for sure
Maybe email the company and seek advice?
As others, I've had a 300 CEL DP (Akra, in my case) in for the last 30k+ miles, never had a light come on.
My bet would be an install issue of some sort.

[squixs]

Just called the shop which installed the DP. They said it's kinda hard to install it incorrectly since the O2 sensors/connectors are specific. And If it would have been an exhaust leak, I would notice that.

So there're saying that my car is probably 'sensitive'. I will follow Anthony1s advice and just drive it for a few days with the CEL to see if the car adapts. Does this CEL have an impact on the car's performance?

[PilotxERAU]

Originally Posted by squixs

Just called the shop which installed the DP. They said it's kinda hard to install it incorrectly since the O2 sensors/connectors are specific. And If it would have been an exhaust leak, I would notice that.

So there're saying that my car is probably 'sensitive'. I will follow Anthony1s advice and just drive it for a few days with the CEL to see if the car adapts. Does this CEL have an impact on the car's performance?

That or you could have bought a much higher mileage cat that is toast. Happened to me on my last car and I vowed to never buy a used cat I didn’t know the history of again.

[nioh_lbbm2]

Kinda sounds like you bought a cat that was used a lot already. Or abused.

[squixs]

Previous owner had it on his stock M2 which still have relatively low miles and I don't think it was used before that on a other car. Would a defect be visible from the outside? Looked fine from both sides but didn't know what to look for

[Poochie]

Some of you guys are lucky to live in a state where they don't sweat emission inspection.

TIL that for OBD2 state emissions testing, the cat not only has to be flowing properly but also be at the correct operating temperature before it allows a "ready" testing phase to commence.

So any aftermarket cat can possible throw off the set stock temperature parameters.

Long story short, just because a sports cat doesn't throw a 'check engine' light doesn't necessary mean you'll pass an OBD2 inspection...
Nice




.

[Poochie]

As far as the OP's issue, I bet the catalyst is burn out, if there is no gasket leaks.

You can't tell it's burned out by physically looking as it but process of elimination could confirm that.

[squixs]

The car makes quite a noise, but a guess thats expected in combination with open flap MPE. Wouldn't the car smell bad when the catalyst isn't working as expected?

[nioh_lbbm2]

Originally Posted by squixs

The car makes quite a noise, but a guess thats expected in combination with open flap MPE. Wouldn't the car smell bad when the catalyst isn't working as expected?

Not necessarily. The cat itself isn't a binary device where it's either on or or off. It's definitely working if it's there but probably just now at a lower efficiency level due to wear and tear from the sound of it.