BMW Engine Malfunction Light Reasons

This dashboard symbol has several names and is often referred to as the engine malfunction light / engine management light, malfunction indicator lamp (MIL), check engine or engine emissions light to name a few.

This warning light covers many faults and will often require diagnostic equipment to be fitted in order to locate the malfunction. Symbol will illuminate on the BMW dashboard along with a check control message. These symbols and messages are as follows:

Control unit	ID code	Fixed indicator light	Variable indicator light	Check Control message	Message in Central Information Display
DME1_DDE1	29			Engine problem! Loss of power	Engine problem. Full engine power no longer available. Drive carefully. Have the problem checked by the nearest BMW Service.
DME1_DDE1	30			Engine! Stop carefully	Engine problem. Continuing driving can cause engine damage. Stop and turn off engine. Contact nearest BMW Service.
DME1_DDE1	31			Increased emissions!	Engine problem influencing exhaust emissions. Have checked by your BMW Service as soon as possible. Static light: Emissions are deteriorating. Flashing light: Excessive misfiring in the engine. Reduce vehicle speed and have the system checked immediately. Engine misfiring within a brief period can seriously damage emission control components such as the catalytic converter.

BMW Engine Management Light Reasons

Though the illumination of an engine management light can indicate various problems, the most common reasons for this light coming on are as follows:

Lambda Sensor / oxygen sensor

This sensor is used to gauge fuel mixture. Sensor sends fuel mixture data back to the ECU (electronic control unit), which in turn calculates whether the fuel mixture is burning rich (less oxygen) or lean (more oxygen) and makes adjustments accordingly. The Lambda sensor is located in the exhaust manifold and monitors emissions. Symptoms of a faulty lambda sensor can be:

• Engine management dashboard light
• Higher fuel consumption due to incorrect fuel mixture
• Engine power not acting as expected – decreased power, slow to respond
• Erratic idle / tick-over
• Starting problems

Coil Pack

The coil pack also called ignition coil (single unit) or spark coil, builds up many thousands of electrical energy / volts which is then released via a signal from the ECU. This energy is sent to the spark plugs which in turn ‘spark’ and ignites the fuel. Symptoms of a faulty coil pack include:

• Engine management dashboard light
• If the coil pack has completely malfunctioned, the car will not start at all
• Many attempts at starting the car is an indication that the coil pack may have a fault
• A coil pack failing to provide any or sufficient charge for fuel ignition may result in unburnt fuel that may cause backfiring or misfiring
• When stopping the vehicle, the engine stalls
• Poor fuel economy
• Erratic tick-over at idle / irregular sounding engine
• Reduced engine power

Air Mass sensor

On the other side of the engine is the mass air flow sensor which measures the amount of air entering the engine. This sensor sends information to the computer and is used estimate how much fuel is needed to mix with air for optimum combustion. Symptoms of a faulty mass air flow include:

• Engine management dashboard light
• Engine becomes difficult to start
• Engine may stall shortly after starting
• Engine pauses under load / acceleration
• Stuttering engine

EGR Valve

The EGR (Exhaust Gas Recirculation) valve recirculates exhaust emissions from the engine back through into the combustion process. Around 5% to 15% is recirculated and this is to ensure that all fuel gets completely burned. Symptoms of a faulty / stuck EGR valve may include:

• Engine management dashboard light
• A smell of fuel
• An increase in fuel consumption
• Engine sounds rough / erratic on idle