120408 bmw b58 fix Thx!. Barbera335 - You are right, problem solved, thank you!!! According to the content of the site you mentioned, it appears to be an error in the electronic part or a error in the charging pressure sensor. Reverse the lines at the pressure converter and this will correct your problem. The diagnosis given to the owner was a catastrophic turbo failure. The BMW fault code 120408 translates to “Charge Pressure Control, Deactivation. I’m having problems with my 340i b58 gen 1. ” Essentially, this code signals that the engine control module (ECM) has detected a problem with the turbocharger’s ability to control the charge pressure properly. Upon inspection the only problem that was obvious was the timing chain. 120408 - Charging pressure control: Switch-off as consequential reaction. At the end of the drive, I got drivetrain malufunction and reduced power. Well I think it's quite clear: you got a failure on the wastegate position sensor. Get the sensor replaced and delete the failures. Thanks Robin750. This issue could be the pressure converter (boost solenoid) that controls wastegate activation using the vacuum system. Can these errors occur on a one-time basis??? There is a test procedure in ISTA for charging pressure, though I'm not sure if that tool supports it. I checked the codes and among the ones i know of, I found 2 key ones: My question is - can these be tied to the spark plugs change or the engine cleanup? I've thrown a new wastegate pressure converter in the car, but still have the code, it was weird. I have seen it before on the N55 engine. The timing chain was still intact; however, the guides were in pieces. i got codes 120308 (boost pressure control, plausibility: pressure too low) and 120408 (boost pressure control: shutdown as a follow-up reaction) these codes appear right after going into limp mode (drive train malfunction). After the warning lamp has occurred, there has been continuous 2 to 3 high rpm and high speed driving, but there will be no warning lamp again. I've also checked and replaced two vacuum hoses with silicon hosing. I have replaced the timing chain. Probably the wastegate has been therefore deactivated and the engine no longer gets the desire boost, triggering the second failure. When I received this vehicle, it was not running. The converter is mounted to the side of the valve cover and the lines were probably switched when the spark plugs were replaced. Hopefully new boost pressure solenoid (s) is the problem. Thx! i got codes 120308 (boost pressure control, plausibility: pressure too low) and 120408 (boost pressure control: shutdown as a follow-up reaction) these codes appear right after going into limp mode (drive train malfunction). snwo ltmpoa moqt lau fkmxnk sltv ndana cyjc rprufrlr kxvdi