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Matt, Mechanical Engineer
Category: BMW
Satisfied Customers: 20389
Experience:  BEng hons Mech engineering, in auto industry 22 years
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I have a bmw e92 325d and the EMF light has come on with

Resolved Question:

Hi, I have a bmw e92 325d and the EMF light has come on with loss of power. I have had my car diagnosed and the following codes have come up P2227 Barometric pressure cuircut range performance, P0236 Turbocharger boost sensor A cuircut range performance, 3ff1 air mass sensor incorrect function, 3f03 boost pressure sensor faulty signal and 4063 air pressure sensor. Could you please give me some advice .
Submitted: 3 months ago.
Category: BMW
Expert:  Matt replied 3 months ago.


I'd start by checking for an airleak after the airflow meter, any air dragged in here isn't 'seen' by the ECU and so not compensated for and can lean the engine out and can also allow the engine to rev up when not desired causing rough running.

As its a mechanical fault it tends not to turn on the fault light and you can sometimes hear a 'hissing' noise with the engine running.

Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts.

The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane around each joint in turn. If the engine rev's up you've found your leak.

Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.

Work your way through each possible joint one at a time and you should find it. I use a slightly flattenedpiece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.

Might also be worth checking the wiring and connector to the airflow meter for any signs of corrosion or damage. you can do a quick fault find if you unplug the meter and run the engine without it.

if the engine condition is the same then chances are the meter or the connection to it is faulty

Air leaks are very temperature dependent as gaps can open or close up as things expand with heat, so the weather and engine temperature can effect them.

This leads them to be quite intermittent in the case of mild leaks

its also worth cleaning the airflow meter by removing it from the car and spraying the exposed sensor wires inside the tube with a brake or switch cleaner - ensure that the cleaner is one of the old fashioned, non Eco type that does not leave a residue

On no account touch the sensor wires with anything physical as they are extremely fragile

Customer: replied 3 months ago.
Hi, thank you for your response. I have replaced the air mass sensor today and then tried to clear the fault codes but wasn't able to do that . I decided to disconnect the battery for a while . After that I drove the car for few miles and managed to clear all the fault codes and my car runs properly now but I am not sure if it was actually a faulty air mass sensor or if the ECU has been reset by disconnecting the battery and my problem will come back again soon. Could you please let me know your thoughts.
Expert:  Matt replied 3 months ago.


I've known a faulty sensor to drag the ECU down and so generate multiple faults so the fact the faults now clear with the sensor replaced kind of backs up the fact it was the issue

as you wouldn't be able to clear it just with the battery disconnection

Expert:  Matt replied 3 months ago.


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Matt, Mechanical Engineer
Category: BMW
Satisfied Customers: 20389
Experience: BEng hons Mech engineering, in auto industry 22 years
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