[bmw335iAFE]

Hello guys. Right now i have 3 stage ECU AFE installed on my BMW 335i 2009 RWD sedan but the problem is that annoying engine light is always on so i was thinking to remove AFE 3 stage piggyback and install JB4!
someone can help me if JB4 will resolve the engine light issue ?

"3 stage ECU AFE works great and i can feel big difference every time i go on stage 2 or stage 3 but some people said JB4 is better than AFE! is that true".

[Smgs1992]

What is the CEL on for? If say it's for downpipes I think you still have to get the DP fix with JB4 however MHD you just check the box for catless downpipes.

[jwalker87]

For JB4, I think the current firmware removed the ability to auto-clear the DP codes. However, if you can get your hands on a previous revision of the software, then that is an option. For example, I am on N54_G5_ISO_32_8 and it still works.

[opjose]

Originally Posted by jwalker87

For JB4, I think the current firmware removed the ability to auto-clear the DP codes. However, if you can get your hands on a previous revision of the software, then that is an option. For example, I am on N54_G5_ISO_32_8 and it still works.

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+—- This!

I am on an N55 with a non ISO JB4 and it too suppresses cel codes.

Note that to pass smog you must disable the JB4 (or MHD) and that causes the cels to reappear and fail the tests.... so DP fix.

[Antetokounmpo]

Originally Posted by Smgs1992

What is the CEL on for? If say it's for downpipes I think you still have to get the DP fix with JB4 however MHD you just check the box for catless downpipes.

No, no, no. Running DP fix is not what you want, it's ONLY for emissions. JB4 gets rid of CEL too.

[Smgs1992]

Originally Posted by Antetokounmpo

No, no, no. Running DP fix is not what you want, it's ONLY for emissions. JB4 gets rid of CEL too.

Was unaware. I run MHD but did basic research on JB4 before choosing

[jwalker87]

For the sake of a holistic answer...

-Current versions of JB4 firmware don't do anything about catless-DPs. You would need something like an MHD or other backend flash to clear them for long-term, routine use. I think; I haven't actually done this, so maybe someone else can chime in with more details.
-Older versions of JB4 firmware had an "autoclear" feature that would automatically clear the catalyst codes when they popped up, preventing you from getting a CEL. However, something is still stored in the system, so if you have OBD-II emissions testing, you will NOT pass using this method.
-DP-Fix wires into the JB4 or stock wiring harness to fool the car into thinking the downstream O2 sensor is reading proper values for having a catalytic converter installed. This is how you pass OBD-II emissions testing with catless DPs. However, there have been reports that long-term use negatively affects the engine's fueling, since it does use both o2 sensor values to adjust targets. The manufacturers of the devices (BMS and VRSF at one point, at least) recommended this as well. So you install it, run through at least one drive cycle, get tested, then remove it. Or at least deactivate it, which is rotating the rheostat fully one way.