When the “Drivetrain malfunction” message pops up it means your BMW’s onboard computers detected a malfunction in the drivetrain system. That is, from the engine up to the wheels. Drivetrain malfunctions are usually, but not necessarily, less severe than Engine Malfunction or Transmission Malfunction warning messages.
Fast Facts⚡ The “Drivetrain malfunction” usually means there is a fault in either engine or transmission.
⚡ Depending on a fault severity, the engine and transmission will switch to limp home mode to prevent further damage.
⚡ Drivetrain malfunction can be from almost benign to very serious. The only way to know is by reading out ECU fault memory.
⚡ If the malfunction affects the emission system, besides the Drivetrain malfunction message, you’ll also see the check engine lights up.
⚡ To reset the Drivetrain Malfunction warning you can cycle the ignition off and on. If the fault is not permanent, the warning message will clear.
Drivetrain Diagnostic Monitoring System
Every control module of the drivetrain system has a virtual model stored in the control unit: DME (Engine Control Module), EGS (Transmission Control Module), GHAS (Differential Control Module), and VTG (Transfer Case Control Module).
For example, the engine control module DME has a virtual engine model by which it manages both the engine operation and performance monitoring. This model represents the perfect engine operation with maximum efficiency.
But, because the engine works in many different operational conditions the diagnostic monitoring system has a specified diagnostic threshold margin for each value.
Here’s what I mean.
Back in 2016 a few BMW M2 owners complained about the Drivetrain Malfunction message popping up at full throttle with almost new cars. The fault memory readout revealed a problem with the turbocharger control:
Charging pressure control plausibility: Pressure too high Charging pressure control: Switching off
The cause of this malfunction was an overly sensitive diagnostic threshold in DME. So, for the next software release (16-07-504) these thresholds were increased and the problem is solved for good.
On the other hand, at about the same time, the N63 V8-powered BMWs suffered from the Drivetrain Malfunction warning message only after a long drive at very light throttle at low RPMs.
The stored error codes usually revealed one or more cylinder misfires.
Again, the problem was in an overly sensitive diagnostic threshold set in the DME and it is solved with a software update.
In both cases cycling the ignition off and back on cleared the Drivetrain Malfunction warning.
When your BMW’s onboard diagnostic system detects a malfunction, it generates the fault code entry in the affected control unit and informs you with a check control message via iDrive and instrument cluster display.
Depending on a malfunction source and the potential damage it can cause, the engine’s power output might or might not be reduced.
What to Do When Drivetrain Malfunction Appears
Since there’s no way to know the source of the malfunction without reading out the fault memory, the only thing you can do is safely stop the car, turn off the engine, and restart it again. If the message disappears, slowly continue the drive and have the problem checked as soon as possible.
Do not confuse the “Drivetrain Malfunction” warning message with the “Drivetrain: Vehicle cannot be restarted,” as there’s a possibility you won’t be able to restart the car. However, any time I got the car with this message, I was able to restart it. So, in this case, do it at your own risk.
If the malfunction message stays on that means the fault is permanent. However, if the engine and transmission work fine, and there are no unusual noises or smells, you can still continue the journey.
No matter what, if you decide to continue driving, drive gently.
Read Out The Fault Memory
When the Drivetrain Malfunction pops up, the fastest way to check what’s wrong is to read out the fault memory with a diagnostic scanner or the smartphone app. Although you probably won’t be able to fix the car at a spot, at least you’ll know the malfunction severity.
For example, if the problem is turbocharger control malfunctioning, you can continue driving with reduced power. Cycling the ignition off and on will usually reset the system and bring the power back.
I don’t use diagnostic apps on the phone to repair the cars, but in this case, they come very handy.
If your dealer or indy uses remote ISTA BMW diagnostics (RITA), they can run the vehicle test over the air and read out fault codes in about five minutes. That way the tech can advise you on malfunction severity and what to do next. This can be very handy if you’re on a road trip.
The remote diagnostics will work for all BMW models equipped with iDrive 4 and later, that is, from the production date of 2014 and an active ConnectedDrive subscription, but not in all markets.
Most Common Drivetrain Malfunction Causes
The causes for the Drivetrain Malfunction warning range from a broken wire up to a burnt piston. However, below is a list of the most common causes that we see in BMW repair shops.
Turbocharger Boost Control
N54 and N55-powered BMWs have been popping up Drivetrain warnings because of turbocharger boost control ever since they hit the dealerships in 2006. The fault codes include both “charge-air pressure too low” and “charge-air pressure too high.” The issue, of course, affects all turbocharged BMW engines, including Diesels.
When driving your BMW, you’ll notice a gross power interruption without any stumbles or misfires. The engine will run smoothly, but sluggish because you’ve just lost half of its horsepower.
When the actual boost pressure values leave the safe threshold set in the DME, the DME loses control over turbochargers, switches them off completely and the engine continues to run in limp home mode.
Single or Multiple Misfires
Misfire happens when the explosive combustion reaction fails to ignite at the proper time. To fire cylinders, your BMW’s gasoline engine relies on four main components: cylinder pressure, fuel, oxygen, and a spark.
The most common misfire causes are leaky injectors, worn ignition coils, spark plugs, vacuum leaks, and compression loss via intake valves.
The DME monitors combustion quality via engine speed deviation for a specific cylinder. Each cylinder firing will slightly speed up the crankshaft. In this way, it can calculate how well each cylinder works. When a certain cylinder slows down the crankshaft, the DME will set a misfire fault code, and, depending on the misfire severity, it will completely switch off the affected cylinder to prevent further damage.
Troubleshooting BMW misfires is an art on its own. The cause of a misfire can be the combination of all factors included or just a bad spark plug.
Low Fuel Pressure
The fuel pressure loss will trigger both fuel pressure and misfire fault codes. Besides the faulty pressure sensor, the most common cause is a worn high-pressure fuel pump (HPFP).
All direct-injection BMW gasoline and Diesel engines use low and high-pressure fuel pumps. In the case of low fuel pressure fault codes, the best way is to go through the ISTA test plan and check all relevant components.
Emission Control System
Although the emission control issues will most often light up the check engine light, in some cases the system can malfunction without affecting the emissions themselves. For example, if a NOx catalytic converter fails to regenerate, if the Diesel or Otto particulate filter clogs, and so on. These are system malfunctions that will eventually lead to component damage and loss of emission control, but for now, they are still doing their job.
The most important thing here is to act as soon as possible to prevent expensive repairs.
Both manual and automatic transmission issues can trigger a Drivetrain Malfunction warning message. For example, if the manual transmission clutch slips, the DME will detect it by comparing the engine output speed and wheel speed.
Using the same principle, the DME can also detect the problem if one of the drive shafts breaks. Drive shaft breaks happen very rarely and are more common with xDrive BMWs.
For automatic transmissions, things are a bit more complicated. But, for the sake of argument, if your transmission lacks a few quarts of oil and when the transmission oil pump sucks air on hard acceleration, the hydraulically actuated clutches won’t be able to deliver desired gear at the right time and you’ll see how the Drivetrain Malfunction warning pops out on your iDrive screen.
Severe automatic transmission faults will usually trigger a “Transmission Malfunction” warning message.
BMW Drivetrain Malfunction is one of those vague warning messages that can mean both nothing and everything. The malfunction in the drivetrain system can be both benign or so serious that will cause thousands of dollars in repairs. So until you read out the fault memory, the message will stay open for individual interpretation.
Nonetheless, it should always be taken seriously and addressed appropriately as soon as possible, even if the warning clears after cycling the ignition.
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