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#1 (permalink) Old 08-05-2007, 10:46 AM
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Exclamation Warning lights

Greetings everyone from a new member....however I do have the following intermittent problem with a warning light,maybe someone can advise,

I have a 2003 bmw 316,the problem generally occurs in the morning,approx 3miles after starting out,the EML warning light comes on and the engine power drops,I then have to switch off and restart the engine,the EML light then goes out,but the engine symbol stays on,the car then appears to drive fine,but with the engine warning light on.The light may go out later that day,or go out on start up the next morning,however the same problem occurs 3 miles into the journey.Any clues as to what the problem might be.
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Barney
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#2 (permalink) Old 08-05-2007, 12:36 PM
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Barney, welcome to bimmerwerkz. The EML indicates a fault detected by the engine management system. This could be any of a wide variety of problems. Usually, the engine management system will not inhibit power delivery until the oxygen sensors have warmed up, which may be why you can drive about three miles before experiencing any trouble.

I am hesitant to give you specifics, since without reading the codes off the car it is hard to diagnose these things. However, you may need now oxygen sensors, or maybe they have come lose. Also, stuff like a bad mass airflow sensor, a camshaft position sensor, etc, etc., could trigger the light.

Describe the drop in engine power, please. My suspicion is that the engine management unit is dropping the car into "limp mode," which is kind of a safe setting designed to allow you to drive to your destination in th event of rather serious engine management problems.

I don't know where you are located, but here in the US, we can take our car to an auto parts store (e.g., Autozone) and they will check the engine fault codes for free, which gives us the reason for the EML. You may need to take it to a mechanic or even the dealership, depending on where you are located.

(I've moved your thread to the E46 section, where it will get more attention from the people who have the most technical knowledge about your car)

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#3 (permalink) Old 08-13-2007, 11:23 AM
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Quote:
Originally Posted by drz
Barney, welcome to bimmerwerkz. The EML indicates a fault detected by the engine management system. This could be any of a wide variety of problems. Usually, the engine management system will not inhibit power delivery until the oxygen sensors have warmed up, which may be why you can drive about three miles before experiencing any trouble.

I am hesitant to give you specifics, since without reading the codes off the car it is hard to diagnose these things. However, you may need now oxygen sensors, or maybe they have come lose. Also, stuff like a bad mass airflow sensor, a camshaft position sensor, etc, etc., could trigger the light.

Describe the drop in engine power, please. My suspicion is that the engine management unit is dropping the car into "limp mode," which is kind of a safe setting designed to allow you to drive to your destination in th event of rather serious engine management problems.

I don't know where you are located, but here in the US, we can take our car to an auto parts store (e.g., Autozone) and they will check the engine fault codes for free, which gives us the reason for the EML. You may need to take it to a mechanic or even the dealership, depending on where you are located.

(I've moved your thread to the E46 section, where it will get more attention from the people who have the most technical knowledge about your car)
A lambda sensor fault is likely, the car should have 2, one pre-cat, one post-cat. As mentioned these take a few minutes to warm up and become operational (go closed loop), at which point they should tell the engine management unit how to adjust the mixture. If one's faulty this would trigger the light coming on and cause a fault code to be stored.

For proper diagnosis you'd need to read the fault code by hooking up an ODBII fault code reader. UK dealers and many independents will have the equipment to do this, although I imagine they charge for the service as they'll see it as a lucrative part of their business. You'll find the ODBII plug under the dashboard, with a pull-down plastic cap, roughly above where the drivers right knee is on a UK RHD car.

I bought an ELM-327 usb fault code reader with connecting leads and software from ebay (find a seller with lots of positive feedback and email details of your vehicle to ensure you get correct model, ODBII, canbus or whichever) to hook up my laptop to my BMW and diagnose / clear fault codes for about £56. Works a treat, on my 2001 325ci, and once you've got it, it saves the hassle and expense of arranging a garage diagnosis, although having said this, it can only diagnose a problem, not change the part to fix it.

Not all faults cause the car to drop into "limp mode" or "get you home mode", I'd suspect if yours is doing that it's best to get the fault diagnosed sooner rather than later, although I used to have a Vauxhall that did that when the (notoriously failure-prone) cam or crank sensors failed, and the cause was (frustratingly) purely with the sensor, not whatever it had failed to monitor. Unfortunately there was no option to rip out and throw the sensor away, despite my previous cars running perfectly well without them.
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#4 (permalink) Old 08-14-2007, 10:52 PM
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Hi Barney,
I m also a new member and owe a 2001-320i in Canada. I had similar problem and I took it to my mechanic who did a diagnostic on the engine. I had the "service engine soon" symbol on but disappeared the next day when I start up the car. Mine is the Intake Camshaft Sensor starts to fail. Therefore the problem is come and go. There are 2 cam sensors, one for intake cam and the other for exhaust cam since our engines are twin-cams. If you crank your car for a total of 9-10 seconds, the warning light will be on. The computer tells you that it shouldn't take that long to fire up. The sensor is a solenoid with magnet. Due to the heat in the engine, they do give up.
Did you take your car for a diagnostic check ?
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#5 (permalink) Old 09-11-2007, 05:21 PM
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Exclamation

Hi Karluver,
Thanks for your help.However I have the problem sorted the unit that controls the sensors was faulty,a new one was fitted and the car is motoring fine now.However,what I did not state was that initially I brought the car to a BMW dealership,with the warning light constantly showing,and they said that they did not know what was causing the problem,and that I would have to leave the car in for further checks.The only conclusions I could draw from this experience was,(a)the design of the test equipment and/or the systems in the car are not fully developed,(b)the staff operating the test equipment are unable to operate it correctly,or(c),the dealership knew exactly what was wrong but were going to rip me off with a host of false repairs.
The mechanic that I did bring it to plugged in some test equipment and diagnosed the problem in a couple of minutes.So,the lesson is,beware of BMW dealerships,especially in Dublin.
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#6 (permalink) Old 09-12-2007, 08:47 AM
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Hi Barney,

I can understand your healthy dose of cynicism, it may not have been quite as simple as that though.

Whilst your mechanic plugged in his electronics and diagnosed the current obvious problem by reading the fault code, as I myself can do, the dealership may have been aware of underlying issues, perhaps this symptom occuring could have a number of different causes, requiring further investigation to establish and rectify the cause of the symptom.

As an example, crank sensor failure was common in certain cars (not BMW), the fault code would indicate crank sensor required replacement, but crucially the wiring to the replacement sensor had to be re-routed away from a hot part of the engine which was melting the wires causing the failure, to prevent premature failure of the replacement part.

Dealers may have extra information and be aware that merely replacing the part which triggers a particular fault code may not be the entire solution.
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