BMW 3 Series misfire caused by faulty engine ECU

BMW 3 series ECU fault causing misfire

Engine misfire is a very common problem across the E90 range fitted with this engine ECU. The vehicle will begin to run rough and develop an engine misfire over one or more cylinders and will often get progressively worse over time.


When diagnosing the problem using scan tools you will find fault codes for injector circuit failure and/or combustion misfire, you will also notice missing injector signals from the ECU.

If left untreated the faulty ECU will become the cause of the BMW E90 not starting and communications to the engine management system may become impossible.


Purchasing a replacement is very expensive, it will require coding to the vehicle at an extra expense and will only be covered by a short one year warranty.


Our BMW ECU repair will resolve all of these issues for a fraction of the cost of a replacement ECU. We will also retain all the original coding so that there is no need for an expensive trip to get it coded. We can test and rebuild your engine ECU within 2-3 working days and provide an unlimited mile lifetime warranty.



Common Failure symptoms:

  • Engine misfire
  • No injector signal
  • Runs rough
  • No start
  • Engine management light illuminated


Common fault codes:

  • 30BA - Injector Circuit Failure 1-3 or DME Internal Fault.
  • 30BB - Injector Circuit Failure 4-6 or DME Internal Fault.
  • 29CE – Combustion Failure Cylinder 2
  • 29CF – Combustion Failure Cylinder 3
  • 29D0 – Combustion Failure Cylinder 4
  • 29D2 – Combustion Failure Cylinder 6
  • 29CC – Combustion Misfire On Several Cylinders


(Can’t find your part number? Check our full engine ECU catalogue for 1 Series, 3 Series, 5 Series or 6 Series)


Test and rebuild:

Each engine management ECU is comprehensively tested on our bespoke HIL (Hardware-In-the-Loop) test rigs. By running the ECU under real-world load and driving conditions we can ensure that, once rebuilt, the engine ECU will out perform OEM specifications.



No need for coding – all programming is retained during test and rebuild.



Our very high lifetime warranty standards encompasses quality control, ESD safety, testing and workmanship, and it’s because of these measures we can confidently and proudly provide a full lifetime warranty on all of our work.



Lifetime unlimited mileage*


How do I get my unit rebuilt?

To pay for the rebuild select your part number above and then click: Get yours rebuilt

Print the payment/booking confirmation email.

Package the engine ECU inside a sturdy box with plenty of packaging material (make sure you include your confirmation email in the box).

Send us your package by tracked courier (the shipping instructions are on the confirmation email).

Once received we will test, rebuild and return your ECU with an unlimited mileage lifetime warranty. (if your unit turns out not to be faulty then we will refund your payment less a small testing fee and return shipping)


What if I don’t want to pay up front?

This is not a problem, if you prefer this option then follow the following steps:

Fill in and submit this test form.

Print the booking confirmation email.

Package the 3 Series ECU inside a sturdy box with plenty of packaging material (make sure you include your confirmation email in the box).

Send us your package by tracked courier (the shipping instructions are on the confirmation email).

Once received, we will test your engine ECU and call you to advise on the outcome of testing, if your unit is faulty and you choose to go ahead with the rebuild then we will take payment over the phone using a debit/credit card.

We will then rebuild your BMW engine ECU and return it to you with an unlimited mileage warranty.

If you require further information regarding this BMW ECU repair then please contact us.

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Comments on "BMW 3 Series misfire caused by faulty engine ECU"
Jason says: 30/05/2024 06:43:00
Trying to sort out problem with 2006 335i,it comes up 30bb fault,which has led me to you,you ok if I pack and send from Sydney ,Australia?
ECU Admin says: 30/05/2024 15:55:21
Hi Jason, that would be great, we deal with customers all around the globe. To get started complete our Test Form above
Howard says: 22/05/2023 15:40:55
Having code 30bb but mosfets are good. 2008 BMW 335i E90 MHD80 ECU.
ECU Admin says: 24/05/2023 09:51:26
Hi Howard, sounds like you require a rebuild, get that over to us and we can resolve that for you
Bongani says: 11/08/2022 11:17:49
bmwe90computer box fail to connect with engen
ECU Admin says: 12/08/2022 09:39:23
Hi, we can certainly look into that for you if you wish to send it in for test and rebuild
Ahmed says: 26/05/2021 17:11:23
My ecu needs replacing Please quote me for plug and play
ECU Admin says: 27/05/2021 09:32:09
Hi Ahmed, for prices please select your part number or vehicle above.
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