Hi everyone,


I’m reaching out to the community because I’m completely stuck with a persistent issue on my 2013 Mini Cooper S All4 R61 with the N18 engine. The car constantly throws error 2CB3 – Boost pressure control, plausibility. The main issue is that the turbo never kicks in. Unless rare, very rare cases for few seconds without any pattern of why and how…. Literally always there is no boost at all, no torque increase, and the car drives like a naturally aspirated engine regardless of throttle input.

Here is everything I have already done or checked:

• Replaced the entire turbocharger unit (brand new)
• Replaced all vacuum lines related to the turbo system and made sure about correct connections
• Installed a new boost control solenoid (pressure converter)
• Verified that the blow-off valve opens and closes properly through ISTA-D
• Verified that the pressure converter opens and closes properly through ISTA-D
• Checked cables continuity from DME to pressure converter
• Reset all turbo-related adaptations via ISTA-D
• Updated the DME software to the latest version
• Performed a full boost leak test – no leaks detected
• Tested the vacuum pump directly – it generates –0.95 bar at idle.
• Cleared the DME fault, but 2CB3 returns consistently after driving just few minutes

During static testing, the wastegate actuator moves correctly via ISTA’s actuator test. However, during actual driving, the turbo is clearly not producing pressure. The TMAP sensor shows about 1.2 bar absolute, but there is no sensation of turbo engagement at all.

I’ve ordered a new TMAP sensor, as I suspect the current one might be reading too high and tricking the DME. I’ve also ordered a manual vacuum pump to test the wastegate actuator dynamically on the road, by applying vacuum and forcing it closed to see if boost finally builds.

At this point I’m honestly out of ideas. I feel like I’ve gone through everything mechanical and electronic that could make sense.

I’d appreciate any insight or suggestions… I’m desperate for a solution. I don’t sleep anymore thinking about it!

 

Check for a blockage on the exhaust side eg melted or collapsed catalytic converter or other blockage.

One thing you don't mention is what boost is actually being generated, what is the MAP psi whilst accelerating? Is there literally zero boost, ie MAP = atmospheric, or is it just very low boost?

 

Actually, I’ve never thought about possible blockage. Shouldn’t it give any error for different pressure?

At idle the pressure is 0.9bar and under acceleration is 1.2 bar maximum but not any feeling of boost.

 

Hello Gents,

I have both good and not so good news to share with you regarding the turbo system.

Good news:
I tested the wastegate operation by connecting a manual vacuum pump directly to the turbo, and it worked. Naturally, a few overboost codes were triggered, but the turbo itself responded correctly.

Following that, I connected the manual pump in series with the original system to monitor vacuum pressure, and it was extremely low. Suspecting a potential issue with the vacuum reservoir, I bypassed it and connected the vacuum pump directly to the pressure converter. This setup performed significantly better.

Now the bad news:
While the car’s acceleration was noticeably improved, for reasons still unclear, I hit 2.5 bar of boost, which instantly triggered multiple alarms. In Sport mode, this kind of overboost seems unavoidable. After the third overboost event, the intercooler piping detached, and I suspect the turbo may have suffered damage as well. I really hope that’s not the case.

My question is: do you think this overboost issue could be related to the vacuum tank bypass, or is it more likely due to something else?

Also, since I bought the car used, I started digging into the DME. The label on the unit shows it is original and running MEVD1722 firmware, but when I check using the VIN, the replacement part listed is MEVD1727. Could it be that someone replaced or modified the DME in the past? And if so, how can I confirm it definitively?