BMW Engine Malfunction Reduced Power (Causes + Solutions)

engine malfunction bmw

The BMW engine is known for its efficiency, reliability, and performance. However, like any other engine, it’s not immune to problems. One common issue encountered by BMW owners is the engine malfunction reduced power warning.

This article will discuss the meaning of this warning, its causes, symptoms, and how to address the problem.

By understanding these aspects, you can ensure your BMW remains in optimal condition and continues to deliver the performance you expect.

What Does Engine Malfunction Reduced Power Mean on a BMW?

When you see the engine malfunction reduced power warning on your BMW’s dashboard, it indicates that the vehicle’s performance has been intentionally limited.

This limitation occurs because the car’s computer, also known as the Digital Motor Electronics (DME), detects a system failure or low-performance issue. In response, the DME activates a fail-safe mode designed to protect the engine from further damage.

This mode can hinder acceleration and may also trigger a check engine light.

Common Causes of Engine Malfunction Reduced Power on BMW

There are several possible causes for the engine malfunction reduced power warning on your BMW. Diagnosing the exact cause requires connecting a BMW scanner to your vehicle’s OBD-II port, located under the dashboard on the driver’s side.

This scanner can read fault codes, providing valuable information about the issue. Some common causes include:

1. Malfunctioning Valvetronic System

Valvetronic is a system found in many BMW engines, designed to eliminate the need for a throttle plate by varying the amount of intake valve lift. If the Valvetronic system malfunctions, your BMW may experience a lack of power and poor throttle response.

Common causes of a faulty Valvetronic system include low system voltages, poor electrical connections, and a sticking eccentric shaft.

Fault codes related to Valvetronic issues include 2A61, 2A63, 2A67, 2A6F, and 2A70. To address this problem, you’ll need to visit a trustworthy BMW mechanic.

2. VANOS Failure

VANOS, an abbreviation for a German-named engine part (variable Nockenwellensteuerung), is a robust system operated by oil-powered actuators. It improves the efficiency and performance of BMW’s intake and exhaust valves, providing increased torque and smoother idle.

VANOS failure is often caused by oil sludge buildup within the VANOS solenoids, resulting from lengthy oil change intervals. Fortunately, VANOS solenoids are relatively inexpensive and easy to replace.

Symptoms of a malfunctioning VANOS system include:

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

Fault codes for defective VANOS solenoids are 2A82, 2A87, P1520, P1523, and P1397.

3. Defective High-pressure Fuel Pump (HPFP)

Newer BMW models, such as the E90 335i, feature engines with high-pressure fuel injection. The high-pressure fuel pump (HPFP) injects fuel into the engine’s combustion chamber, allowing your BMW to run efficiently.

If this pump fails, no fuel will be pumped into the engine, leading to symptoms such as a yellow ½ check engine light and hard starting with long cranking.

Acceleration and power output are heavily affected by HPFP failure. It’s essential to replace the damaged pump as soon as possible.

Fault codes for a bad HPFP include 2FBA, 2FBF, 29DC, and 29E2.

4. Bad Oxygen Sensor

BMW engines utilize upstream O2 sensors to achieve optimal performance. These sensors communicate air-fuel ratio measurements to the DME, which adjusts accordingly.

A bad oxygen sensor can trigger the engine malfunction and reduce power warnings.

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

Signs of a faulty oxygen sensor include:

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

To address a faulty oxygen sensor, you should take your vehicle to a specialized BMW mechanic.

5. DME or Data Network Problems

BMWs feature a DME (Digital Motor Electronics) module, a computer that controls all vital aspects of the engine’s operation.

It communicates codes and instructions to multiple systems within the vehicle. If this communication network is 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

6. Faulty Ignition Coils

Ignition coils can fail for various reasons, such as age and wear, or due to electrical issues. A malfunctioning ignition coil will cause an engine misfire, which can lead to the engine shaking when accelerating. Driving with faulty ignition coils can damage the catalytic converter, so it’s not recommended.

Ignition coils are relatively easy to replace, and it’s a good idea to keep spare coils on hand. Loose connectors to the ignition coils may also trigger the engine malfunction reduced power warning.

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

7. Timing Chain Failure

The timing chain is a metal chain located inside your BMW’s engine. It synchronizes the rotation of a shaft and the opening and closing of valves in the engine. If the timing chain fails or becomes stretched, it can cause severe engine damage.

A yellow ½ check engine light and reduced power sign may indicate timing chain failure. If you see a red ½ check engine light, it means the timing chain experienced a significant jump. In either case, turn off your vehicle immediately and contact your technician.

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Symptoms of Engine Malfunction Reduced Power on BMW

If your BMW is experiencing engine malfunction and reduced power, you may notice the following symptoms:

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

Can You Drive with Engine Malfunction Reduced Power?

While it’s possible to drive your BMW with engine malfunction reduced power, it’s not recommended. The vehicle’s performance will be limited, meaning the engine will not operate at full capacity.

This can lead to poor acceleration, excessive gas mileage, and jerky gear shifting. It’s best to take your BMW to the nearest service center for a complete vehicle analysis.

How to Diagnose and Solve BMW Engine Malfunction Reduced Power Issues

To diagnose the cause of your BMW’s engine malfunction reduced power issue, you’ll need to connect a BMW scanner to your vehicle’s OBD-II port. This will provide you with fault codes related to the problem.

Once you’ve identified the cause, you can take the appropriate steps to address the issue, whether it’s replacing a faulty component or seeking professional assistance from a BMW mechanic.

Preventing Engine Malfunction Reduced Power Issues

Regular maintenance is crucial to preventing engine malfunction reduced power issues on your BMW. This includes regular oil changes, spark plug replacement, and checking the condition of components like the timing chain, ignition coils, and oxygen sensors.

By keeping your BMW well-maintained and addressing any issues promptly, you can avoid engine malfunction reduced power problems, and ensure your vehicle continues to deliver the performance you expect.

TIP for BMW Engine Malfunction! Reduced Power; Fault Error Trouble Code 2C57 >> Check out the video below:


Understanding the causes and symptoms of engine malfunction reduced power in your BMW is essential to maintaining your vehicle’s performance and reliability.

By identifying and addressing issues early, you can prevent more significant problems from developing. Regular maintenance and timely repairs will help ensure your BMW remains in top condition, delivering the performance and driving experience you expect from this prestigious brand.

Steve P.

Steve is an automotive technician, technical writer, and Managing Editor. He has held a lifelong passion for cars, with a particular interest in cars like the Buick Riviera. Steve is based in Boise, Idaho.

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