SOLVED! N55 - Emissions Shop Can't Communicate with ECU - New Owner (STL)

[DeadlyDrop]

Hello.

New owner of 135i.

Car has aftermarket downpipe with chargepipe installed.
It currently does not throw CEL light.

Found inspection station where they basically cheats OBD2 emission readiness test. All the emission parameter is ready but for some reason it does not pass emission. Did drive cycle again and still no luck.

Shop says emission system can not communicate with car's computer.
They are suggesting maybe car is tuned.

But there is no sign of JB4 or other piggyback tune installed.

Will attach carista emission scan result one before going to shop and after going to shop.

UPDATE: Problem finally solved! It turns out that previous owner had MHD stage 1 plus tune. It doesn't make sense because car has downpipe and with downpipe you can advance to stage 2 right away. Anyway, purchased MHD app from google store and reverted it back to stock and everything is good now! Never been this happy to see CEL light haha.

Thank you all for helping me out!!

[The Wind Breezes]

Can't communicate with computer usually means JB4 is installed. It's probably in invisible mode or whatever and they didn't bother to check the wiring loom. Or you have a flashtune that locked the OBD port.

[DeadlyDrop]

Originally Posted by The Wind Breezes

Can't communicate with computer usually means JB4 is installed. It's probably in invisible mode or whatever and they didn't bother to check the wiring loom. Or you have a flashtune that locked the OBD port.

Thank you for your reply!

I looked through engine bay and i cant find jb4 module anywhere..
Is it possible that flash tune such as MHD tune can prevent it from reading ECU?

I also tried pressing down arrow and volume down button at the same time and it still doesn't do anything. So I believe chance of having JB4 is low.

But still thank you so much!

[Elboz08]

I just had my car smogged while still on the MHD 2+ tune. I had the Cat still installed tho.

[TM9030]

My car had the same issue...I found out the previous owner had flashed the car with an MHD tune.

It's weird, I've read that some people have no issues passing smog with an MHD tune, but some do.

[DeadlyDrop]

Originally Posted by TM9030

My car had the same issue...I found out the previous owner had flashed the car with an MHD tune.

It's weird, I've read that some people have no issues passing smog with an MHD tune, but some do.

I think its MHD, going to flash tonight and see where it takes!
But at this point it looks like its MHD forsure.

[TM9030]

I think its MHD, going to flash tonight and see where it takes!
But at this point it looks like its MHD forsure.

Was MHD the problem?

[DeadlyDrop]

Originally Posted by TM9030

Was MHD the problem?

Yes it was! Apparently car had stage 1+ tune on it. MHD was preventing emissions from communicating with ECU. I restored everything back to stock thru MHD flasher app. Now car shows CEL light for cat and everything. Ready for inspection!

[MattH]

So I had full bolt on and catless downpipe a Cobb tune which eliminates the downpipe sensors...Two years ago smogged the car with the tune and FBO parts...it passes. This year whole different story: Smog technician who did the test last year tells me the car has been Flagged and needs to go to referee. 3 weeks to get an appointment...Smog tech couldn't tell my why it was flagged. I get my appointment and it mentions that my car needs to be reflashed back to factory. Come into the appointment with all corrections and proof of service with an invoice. In reality we removed all the FBO parts, took me a few weeks to find where I had hidden the stock parts: intake, down pipe, charge pipe, intercooler, cat back. I have to move my appointment another 2 weeks goes by...My car is then finally ready: all stock parts are back, Cobb tune "uninstalled" and changed to factory. Well today I fail my smog referee because some code doesn't match the factory code...suggestion: have BMW dealer reflash ECU and bring it back (prob another 2 weeks and no use of car) Contacted my local stealership, they want $188 to reflash but says "no guarantee it will fix the issue" Im seriously now thinking I need to scrap my damn car because the State of California hates modified 135's? Called Cobb: tech tells me uninstalling the Cobb tune would revert the car back to stock. I explained there is some code bullshit that doesn't match some other bullshit. The guy just says maybe someone didn't save the original tune to the tuner?? I'm like seriously, WTF? Between the smog tech's, smog referees, tuners, and the dealership everyone pointing fingers at the other while Im spending my money and not driving my car.

[bbnks2]

Originally Posted by MattH

So I had full bolt on and catless downpipe a Cobb tune which eliminates the downpipe sensors...Two years ago smogged the car with the tune and FBO parts...it passes. This year whole different story: Smog technician who did the test last year tells me the car has been Flagged and needs to go to referee. 3 weeks to get an appointment...Smog tech couldn't tell my why it was flagged. I get my appointment and it mentions that my car needs to be reflashed back to factory. Come into the appointment with all corrections and proof of service with an invoice. In reality we removed all the FBO parts, took me a few weeks to find where I had hidden the stock parts: intake, down pipe, charge pipe, intercooler, cat back. I have to move my appointment another 2 weeks goes by...My car is then finally ready: all stock parts are back, Cobb tune "uninstalled" and changed to factory. Well today I fail my smog referee because some code doesn't match the factory code...suggestion: have BMW dealer reflash ECU and bring it back (prob another 2 weeks and no use of car) Contacted my local stealership, they want $188 to reflash but says "no guarantee it will fix the issue" Im seriously now thinking I need to scrap my damn car because the State of California hates modified 135's? Called Cobb: tech tells me uninstalling the Cobb tune would revert the car back to stock. I explained there is some code bullshit that doesn't match some other bullshit. The guy just says maybe someone didn't save the original tune to the tuner?? I'm like seriously, WTF? Between the smog tech's, smog referees, tuners, and the dealership everyone pointing fingers at the other while Im spending my money and not driving my car.

When you roll into an emissions shop with a cat code delete it's pretty easy to be flagged... the cat will read as "not found" on the OBD machine which pretty much guarantees to the State that you modified your emissions equipment. There are no cars in the united stated that don't have a catalytic converter. Some states must care enough to flag these cars I supposed. Here in NY the mechanic just slaps the emissions sticker on since you passed the OBD test lol. That's just my guess as to why/how you got "flagged."

Scrap the car? Being a bit dramatic now... how about you just don't commit a federal crime? You installed shit on your car that cheats emissions and now you're complaining that emissions inspectors can't tell you how to fix your car lol... seems kind of silly when you say it that way, doesn't it? There are CARB legal high flow cats on the market... or, you can just re-install the stock catalytic converter to pass emissions and then go back to catless after. Have COBB/Tuner send you another tune with the cat check enabled again so the car throws the proper CEL, or, uninstall the tune before going to the emissions shop.