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The BMW 120d e82 2010 model with the N47 engine has a half yellow engine management light. This issue has been diagnosed using a code reader.


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Greetings, esteemed individuals.

I previously had an e92 that remained operational until it reached a mileage of 160,000.

The automobile I now own is a BMW 120d e82 m sport coup with an N47 engine. I like to do oil and air services on it every 7-9k miles. The vehicle has accumulated 108,000 miles and was purchased for 58,000 miles.

Around one to two weeks ago, I began seeing the occurrence of a partially yellow engine management light and a decrease in engine power. I have observed that this issue often arises when the vehicle is started in the morning, particularly in the month of November.

Typically, when I begin the engine, I allow it to idle in order to get a somewhat higher temperature.

The idling noise is acceptable, but there is a slightly higher level of noise chatter than usual. With the N47 engine, it is still possible to hear some chain noise, which is generally considered normal. However, if the noise becomes more pronounced and aggressive, it may indicate a problem.

I will be replacing the oil and filter on Saturday, which will result in the renewal of the previous oil service performed at about 97,000 miles to the current mileage of 108,000. Additionally, I will personally replace the air filter.

I have examined and disconnected the MAF sensor, but it has not produced any MAF contact cleaning using a spray or other method. I am now beginning to inspect the pipes and other components.

Can anybody provide insight into the potential causes of the engine management light illuminating in the mornings, which often resolves itself over the course of driving or reappears?

I would highly appreciate any suggestions about the potential reason.

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Issues related to the plausibility of air mass and errors in the exhaust pressure sensor, Essentially, it refers to the observation of a discrepancy between the intake of air and the pressure of the exhaust.
There may be an air leak somewhere between the Mass Air Flow (MAF) sensor and the engine. It is advisable to inspect common areas such as the boost pipes, input to the turbo, and the breather hose.
Additionally, ensure that the narrow steel tubing connecting the manifold to the pressure sensor is not obstructed.
The vacuum sensor on the brake booster is designed for the stop-start system, therefore there is no need to be concerned about it.

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According to @LimeLing , it seems like there may be a leak. The engine check light is triggered by the mass air flow and exhaust gas pressure codes. The rest are of lesser importance and you may choose to examine them at a later time.

The intake system has many components that may be responsible for the problem.


The second item, known as the breather hose or blow by hose, becomes fragile and develops fractures.
Occasionally, the Charge Air Pipe (Item 10) develops fractures in close proximity to Item 8 (Charge air temperature sensor).

The mass air pressure sensor sometimes becomes obstructed (Item 6). It is a simple and efficient process to remove and clean.

Examine the sensor located in the mass air flow metre, which is often referred to as the hot film mass metre by BMW. It should be free of dirt and impurities since it is positioned downstream of the air filter.

While I have reservations, it is possible that the problem might also be attributed to a malfunctioning EGR valve. I believe that there may be other malfunctions associat

ed with the EGR valve.


Do you possess ISTA+ or the capability to do several tests?ISTA+ offers several tests that may be performed to identify the problem. However, it should be noted that some tests may need the use of oscilloscopes to examine signals, which I choose to omit.

Additionally, ensure that the air filter housing is well sealed.

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This is a typical issue caused by carbon blockage, resulting in unrealistic air mass to EGR codes. I have experience in installing pre-turbine pressure sensors. If the banjo is released, then you may thoroughly clean the pipe with a rod. If a cordless drill is used, an old bike brake Bowden cable may effectively transfer the carbon.


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Thank you everyone, I will examine the matter when I have more illumination. Successfully inspected the airbox and MAF (Mass Airflow) sensor, disassembled the airbox housing by removing two bolts, and began troubleshooting from that point. However, no apparent problems were seen in that area. Consequently, I reassembled the components, reset the error code, and proceeded to test the vehicle, but the issue persisted.

I will examine the other sections at my earliest convenience.

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