The 30FF BMW fault code is one you do not want to see on your BMW. Unfortunately, if you are here, I'm guessing you've got the dreaded code and are looking for answers and hoping those answers don't come with big dollar signs. The 30FF code will usually read "DME: Turbocharger, charge-air pressure too low". If you got this code, your N54 is not running enough boost or is running "underboost".
There are a number of things that could be causing this issue: chargepipe, boost solenoids, vacuum lines, actuators, bad turbos, etc. Before you go dropping thousands of dollars replacing your turbochargers, follow our diagnosis guide to determine whether it really is the turbos having gone bad, or if it might be caused by a smaller and cheaper issue.
30FF Low Boost Symptoms
- Lack of power, sluggish acceleration
- Stalling at idle or rough idling
- Difficulty starting the engine
- Engine logs showing "unmet target" boost levels
- Wastegate rattle
Causes of 30FF Fault Code
- Bad turbochargers (worst case scenario)
- Leaking boost somewhere pre-turbo. This can be caused by:
- Cracked or leaking piping connecting the intake, intercooler, chargepipe, BOV's, or diverter valves
- Leaking vacuum lines
- Bad boost solenoids
- Loose actuator rod
Diagnosing and Repairing 30FF Code
Before you go replacing your turbos, go through this checklist to ensure you aren't just leaking boost from a pipe or vacuum line. The order you do this in doesn't matter, but make sure you check each one of these things before you blame it on the turbos.
1. Inspect piping for the intake, chargepipe, diverter valves
Check all the piping on the bottom right side of your engine: intercooler piping, intake, diverter valves, BOV's (if you have one), etc. If you have a serious leak, you should be able to feel it with your hand, but be careful doing this and only do it on a cold start to prevent burning your hand. Alternatively, you can follow a more advanced guide such as this: https://www.n54tech.com/forums/showthread.php?t=13114
If you notice a leak in any piping along the way, get yourself a new OEM replacement part.
If you have a leaking pipe, you will likely get the 30FF code immediately upon startup. This is the easiest way to diagnose if it is piping as other issues will usually only give you 30FF after you start driving around. If you already have the code, clear the code and then re-start the engine to see how quickly the code reappears.
2. Check your vacuum lines
The turbo wastegate is responsible for how much boost your turbos produce by regulating how much air reaches the turbo. Once the air hits the target boost level, the wastegate opens which results in the air bypassing the turbo completely. This requires the wastegate to know how much boost the turbo is creating. The wastegate knows this because it is connected to the turbo through vacuum lines.
If your vacuum lines are leaking or not functioning properly, the wastegates can remain open, resulting in all of the air bypassing the turbo, thus no boost.
Great diagram to help identify and check vacuum lines: https://www.e90post.com/forums/showthread.php?t=894084
3. Replace your N54 boost solenoids
The boost solenoids work in conjunction with the vacuum lines to control boost pressure. To be fancy, the solenoid is used to bleed boost pressure off of the hose that controls the wastegate actuator, which is what controls the opening and closing of the wastegate.
Symptoms of Bad N54 Boost Solenoids
- Shaky starting the engine
- Noisy/loud boost solenoids (most obvious)
- 30FE engine fault code
- Wastegate rattle
- Log shows unmet target boost levels and very low PWN and WGDC levels
- 30FF will appear after driving for a little while
Replacement Part: https://www.bmwpartsfactory.com/PIERBURG/244/11-74-7-626-350
Make sure you use the OEM Pierburg boost solenoids (in the link above). Don't buy some cheap Amazon ones.
Guide: there are no true replacement guides, but this thread will be helpful: https://www.e90post.com/forums/showthread.php?t=894084
4. Adjust your wastegate actuators
As mentioned above, the wastegate controls airflow either into the turbo, or bypasses the turbo to control the amount of boost created. The most obvious symptom of a bad wastegate actuator (or a loose one I should say) is a "TICK" noise upon startup. You'll usually hear multiple tick sounds.
Guide on adjusting acuators: https://www.e90post.com/forums/showthread.php?t=176269
5. Replace your turbos
If you've done everything above and still haven't been able to resolve your 30FF fault codes, then you have bad turbos. At this point, you have a few options:
- Replace your OEM turbos
- Get upgraded twin turbos
- Send it on a single turbo setup
Getting OEM replacements is going to be the cheapest option, but you can get some solid stage 1 or stage 2 upgraded twins for not much more and get some power out of it.
If you are thinking about getting upgraded turbos, read this ultimate guide here: BMW N54 Updated Twin Turbo Guide