For a change: my X5 mil/cel/motor lamp will not light

[GerX5]

Hi folks,

I'm new here after having spent hours of reading interesting stuff regarding mil/cel/motor lights that light and what to do about it to repair the cause. I hope to find here a solution for the problem that I experience with my car. And of course, I hope to contribute to the content of this forum if it can be of help.

I'm a 60 years young first time BMW driver, since 2 months owner of a 2005 X5 3.0D 58k kms (checked and explainable). The problem I experience: the MIL/CEL/Motor lamp will not light when starting the car, nor if a related code occurs that normally would lead to a lighting lamp. Before writing the story down (it will take some time to inform you about all the steps undertaken yet and the results found), I would like to ask whether there is a thread to a similar item that I must have missed during the searches I did.

Curious for your responses, I give you my warm greetings from a cold Netherlands. GerX5

[SlickGT1]

I am curious who screwed with your car. There are a couple of things to check.

1. Some prick might have covered the bulb with electrical tape.
2. Maybe covered up the opening to it.

I think you should take the cluster out and take a closer look.

[dhyrk3]

Perhaps try doing a lamp test. And if the wont still go off then it mit be Slick's number 1

[GerX5]

There started the first part of the search: is the cluster what it should be.
Yes, it is tested by a expert on BWM clusters in Germany: definitely OK. In the self test of the cluster the CEL/LIM/motor lamp lights!

[SlickGT1]

Ok, the expert that tested it for you, if he is capable, have him connect to your cluster with NCS Expert and check if someone disabled the light for what it should be reporting.

Speaking of which, what code exactly didn't it light up for?

Can you just unplug your maf and see if the light will turn on?

[GerX5]

As stated: I'm new here and forgot to tell that English is not my mother tongue. So give me the time to learn abbreviations (and more). Could you explain the used abbreviations for me, please, like NCS and maf?

When I bought the car I was from a technical point of view a complete "stranger" to BMW. So I asked a local BMW dealer for help: checking (for a cheque) if the car is save to buy from a private person. Car connected to testing system, readings were OK, no problems found, sound for its age and KM's. With my knowledge level by then of testing reports etc. I made the deal and started to drive the car. No problems so far.

A problem came up during the yearly state examination of the car a month later, something like the German TUV. The car was rejected because of a non working LIM/CEL/motor lamp: not during turning the key to ACC and not while a code was logged: P4501. It caused the start of the long search since mid November to tackle this problem together with/lead by one of my colleagues with many years real BMW experience on service manager level, having started an own company in analysing technical failures in automotive systems (so mechanical and electronical). I have learned a lot of him last months, while trying to get to the bottom of the problem that came up, using his extensive testing and measuring equipment. Looking back in the "deep" layers of the code memories in the car electronics, we could see there were another 2 failures: the alternator lamp does not light and even the oil pressure lamp does not light when turning the key to ACC. In the past there have been codes occurred forced by a drained battery, that was replaced by a new one without clearing the code than.

I will give for now a short overview of the first activities we deployed to gather insights. Probably it is more wise to write hereafter the complete story to the state at this moment: a) to inform you members to gain focussed replies and b) to prevent that this lead will become more than 15 pages of replies on the many details that already are tackled by our activities you can only know of, when I write the complete story and post that here.

All parts of the EGR system are checked in between, as well by computer testers as well as by our eyes, testing procedures and sound minds. The expected carbonization of essential components of the air intake system appeared not to exist (eg checked with endoscope and removing system components between the turbo and the inlets in the cylinder head. The EGR valve (vacuum operated) is cleaned and with separate vacuum systems tested for operation: OK. The vacuum system of the X5 is tested for proper operation in the control of EGR valve: ok, pulsating building up the vacuum at the time that more exhaust gases should be added. It is also determined that the system produces more vacuum than is necessary for the EGR valve to open 100%. And no vacuum leaks and leaks in the air intake.

So, from a technical point of view there was and is no reason for lighting the motor lamp. Although, the code shows up repetitively. Making extensive test drives with testing equipment connected to the car, recording live data, at first we drew the same conclusion: nothing wrong, no code, calculated air mass is almost 100% matched by measured air mass, if necessary corrected by exhaust gasses via the EGR valve. And then all at a sudden: the % operating of the EGR valve drops till 5% and after a short time the code P4501 shows up again: negative air mass. Reset of codes etc. Doing the procedure over again while looking intensively to the live data: nothing wrong up to 2000 rpm. EGR system works perfect, accelerating to 2100 rpm, keeping it there and look: code P4501, the % operating (forced by the engine management system) of the EGR valve remains 10-20 seconds 5% and then the system takes up and works perfect, like described as before. If the code occurs, the testing system reads in the car system CEL/MIL/motor lamp is activated. However, the cluster shows no lighting motor lamp. Because of a remark in one of the official testing reports regarding the air mass meter (sometimes failing within given boundaries) we replaced it by a new one. The results remain the same. So we have a spare one for better times ;-)

We have the impression that the engine electronics force the problem in twofold: it causes a command to the EGR valve to drop operating level to 5% which causes the P4501 code and consequently prevents the motor lamp to light. This raises two questions: is there a method to check if the software is manipulated and what are the opportunities to reset the original software?

For today: so far so good.

Rgds, Ger

ps If we simulate "No oil pressure" by connecting the lead of the pressure sensor to earth, immediately a text message pops up in the screen: stop etc. no oil pressure or something like that while the oil pressure lamp is not lighting.

[GerX5]

Hi folks,
just to let you know: It's still there, the MIL that lits. From a mechanical point of view a perfectly running engine, with superb fuel consumption. From an electronic point of view: not to trace what where happens.
Because of the expected manipulation of the engine management systems software, once the car was overnight at a BMW dealership. All software replaced and updated where necessary. Engine runs even more smoother as before, but bringing it to 2100 RPM for 30-60 seconds, the P4501 fault occurs again, over and over.
Question: somebody of you familiar whether one can compensate or adjust the EGR/Fuelsystem with some units just enough to remain "in balance"?

Curious for your answers, I'll give you my best regards.
Ger

[LVP]

Have you pulled the instrument cluster out of the dash and pulled it apart? Mine had the light covered with tape. It was lighting up just fine, but the tape covered it from view. They are not bulbs, so if they truly are burnt out, you'll need someone capable of repairing electronic circuit boards.

[GerX5]

Hi LVP,

the cluster was the first thing that we had examined very carefully (see earlier contributions).

Thanks.
Ger

[GerX5]

Hi folks,

just to let you know: the problem of the ever occuring code P4501 has been resolved! Remember I wrote some time ago that the engine was OK from a mechanical point of view and also from an electronic point of view. After determining the circumstances that caused the fault code P4501, we decided to adjust the EGR value via the service part in the tester by a certain percentage. Back from a long trip to and in the mountains we can conclude: the P4501 code did not occure for once during several thousands of km's. Case closed!