bmw engine malfunction reduced power

BMW Engine Malfunction Reduced Power: Symptoms and Causes

The BMW engine is efficient, reliable, and robust. It is indeed one of the best out there. However, the engine is not immune to problems despite its outstanding performance. One issue common to BMWs is the engine malfunction reduced power. The major causes of this issue include:

  • Bad oxygen sensor
  • Clogging of the catalytic converter 
  • Loose connections to engine sensors
  • Faulty VANOS
  • Defective Valvetronic system
  • A weak battery

This article will discuss what BMW engine malfunction reduced power is, what causes it, and the symptoms to look out for. Also, I will provide you with fixes to some of these problems.

engine fault reduced power message
iDrive on your car might exhibit this message when it got engine malfunction reduced power. Credit: big_gtr (

If you want to know more about this  BMW engine malfunction, read on.

What Does Engine Malfunction Reduced Power Mean on BMW?

If you notice the engine malfunction reduced power warning on your BMW, it implies that your vehicle’s performance has been limited intentionally. This limitation happens because the car computer sets off this warning signal whenever it detects a system failure or low performance. This mode hinders vehicles from accelerating. 

Various vehicle manufacturers put this warning as a fail-safe mode intended to protect the engine from further damage. Keep in mind that this engine defect can also trigger a check engine light on your BMW. 

Depending on your BMW model, the content of the error message may be slightly different. However, they all carry the same idea. Here’s what it looks like, “Full engine power no longer available. Possible to continue. Drive moderately. Have the problem checked by the nearest service”. 

Can I Drive with Engine Malfunction Reduced Power?

Yes, you can. However, it’s not recommended. Driving with engine malfunction reduced power does not pose any significant risk to you. Nevertheless, it won’t be an enjoyable ride due to certain reasons. Seeing as the performance of your BMW has been limited, it means that your engine will not operate at full capacity. 

This may lead to poor acceleration and excessive gas mileage. Additionally, your BMW may be jerky when shifting from gear to gear. I recommend taking your BMW to the nearest BMW garage for a complete vehicle analysis. 

Read more: What Is DME on a BMW? Symptoms and Causes of a Faulty DME

Signs of Engine Malfunction Reduced Power on BMW

symptoms of engine malfunction reduced power
Your BMW might display these symptoms when it got Engine Malfunction Reduced Power.

Here are the symptoms of engine malfunction reduced power on a BMW:

  • Reduced engine power
  • Drivetrain malfunction
  • Increased emissions
  • Decreased output
  • Vehicle going into limp mode
  • Engine light malfunction

Causes of Engine Malfunction Reduced Power on BMW and What to Do

Causes of engine malfunction reduced power
Use a BMW scanner to determine what exactly your car is suffering.

I have compiled a list of problems that could trigger the engine malfunction reduced power fault on your BMW below. To be sure about the cause of this message, connect a BMW scanner directly to your vehicle’s OBD-II port to read the fault code. You can find the OBD-II port under the dashboard on the driver’s side.

Malfunctioning Valvetronic

What is Valvetronic? BMW’s Innovative Throttle System.

Valvetronic is a system common in the engines of various BMWs. The function is to eliminate the need for a throttle plate by variating the quantity of intake valve lifts. If the Valvetronic malfunctions, your  BMW may experience a lack of power and poor throttle response. 

Typical causes of a bad Valvetronic system include low system voltages,  poor electrical connections, and a sticking eccentric shaft. This may lead to various fault codes such as 2A61, 2A63, 2A67, 2A6F, and 2A70.  The Valvetronic system can be deactivated or go into limp mode if this fault code shows up. You will have to visit a trustworthy BMW mechanic to address this.

Vanos Failure 

Vanos system
VANOS system is designed to improve the efficiency and performance of BMWs’ intake and exhaust valves. Credit:

VANOS, an abbreviation for a German-named engine part (variable Nockenwellensteuerung), is a robust system operated by oil-powered actuators. The VANOS system is designed to improve the efficiency and performance of BMWs’ intake and exhaust valves. Additionally, it provides your car with increased torque and smoother idle. VANOS failure is usually caused by oil sludge build-up inside the VANOS solenoids.

Lengthy oil change intervals often cause this sludge build-up. Fortunately, VANOS solenoids are relatively cheap.

Here are some symptoms of a malfunctioning VANOS:

  • Power deficiency 
  • Check engine light on
  • Lowered performance 
  • Reduced fuel efficiency 
  • Stalling in cold weather 
  • Cold starting 

You may also notice a tapping noise originating from the VANOS area. Fault codes for defective VANOS solenoids are 2A82, 2A87, P1520, P1523, and P1397.

Defective High-pressure Fuel Pump (HPFP)

Replace the defective HPFP as soon as possible to inject fuel into the combustion properly. Credit:

A defective HPFP can trigger engine malfunction reduced power. The high-pressure fuel pump injects fuel into your engine’s combustion chamber, allowing your BMW to run efficiently. If this machinery fails, no fuel will be pumped into the engine. Symptoms include a yellow ½ check engine light and hard starting with long cranking.

Acceleration and power output are affected heavily due to HPFP failure. Ensure to replace the damaged pump as soon as possible.

Here are the fault codes for a bad HPFP: 2FBA, 2FBF, 29DC, and 29E2.

Read more: How Much Does It Cost to Change Brake Fluid in Your BMW?

Bad Oxygen sensor

The BMW’s engine uses upstream O2 sensors to achieve maximum engine performance. These sensors communicate air-fuel ratio measurements inside your BMW’s engine to its DME to adjust accordingly. A bad oxygen sensor can also trigger the engine malfunction reduced power alert.

Fault codes related to oxygen sensor failure are 2C9C or P0171 to P0174

Signs of a faulty oxygen sensor include:

  • Poor engine performance 
  • Overheating 
  • Misfiring 
  • Bad gas mileage 
  • Pungent smell from exhaust 
  • Check engine light on 
  • Engine noise

What to do:

Although you can occasionally clean the O2 sensor of your BMW’s engine as a maintenance routine, you cannot fix damaged oxygen sensors yourself. I recommend taking your vehicle to a specialized BMW mechanic. 

DME or Data Network Problems

A DME is considered a BMW’s brain. It manages all critical things of the engine in order to ensure the stable operation of the vehicle.

BMWs come with a DME (Digital Motor Electronics), a computer that controls all vital aspects of the engine’s operation. It works by communicating codes/instructions to multiple systems. If this communication network gets interrupted or the DME fails, your car may automatically enter the engine malfunction reduced power mode.

Common DME malfunction symptoms include:

  • Stalling
  • Poor performance 
  • Misfires 
  • Check engine light on 
  • Bad fuel economy 

Faulty Ignition Coils

Several factors can cause ignition coils to go bad. A malfunctioning ignition coil will trigger an engine misfire, which will cause the engine to shake when accelerating. When your BMW’s engine misfires, it is likely to cause damage to the catalytic converter. So, I do not recommend driving with faulty ignition coils. 

But there’s good news. You can replace ignition coils easily. I advise having spare ignition coils in case one fails. Also, a loose connector to the ignition coils of your car’s engine may set off the alert.

Fault codes associated with damaged ignition coils are P0300 to P0306.

Here’s a video on how to safely replace damaged ignition coils on your BMW’s engine. 

How to change Ignition Coils on a BMW

Timing Chain Failure 

The timing chain is a metal chain located inside your BMW’s engine. Failure of this component can result in severe engine damage. Although it is designed to be a life-long item, with time, the timing chain gets stretched. If this happens, the chain may jump a tooth or more. This jump can cause your engine to make rattling noises.

This malfunction will trigger a yellow 1/2 “check engine light” and a reduced power sign. Besides, A red 1/2 “check engine light” means that the timing chain experienced a significant jump.

I recommend turning off your vehicle immediately after you notice this warning and calling your technician. 

Read more: BMW Charging Malfunction: Causes and Solutions


Thanks to this article, you now know the common causes of this problem. I recommend having a BMW scanner as it will go a long way in helping you detect faults in your car easily. If your BMW exhibits any of the symptoms mentioned above, it’s time to perform a complete engine diagnosis. That way, you can detect any faults before it escalates into a major engine problem. 

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