This was a very interesting diagnostics case.

At first – I didn’t know anything about the current car or its problems. Yes, N54 series engine, so: USA market. Yes, bought recently (judging by license plate), but – no information regarding some specific problems.

The diagnostics itself also wasn’t trivial.

And finally – the buyer of the car got in touch with me and sent some very interesting information regarding the car’s history. This was as an exam for myself. In some way – the owner of the car tested me indirectly (or maybe by intention). But I’m only glad about the challenges.


How did I succeed? Read further!

The car: E90, USA market, N54 engine.

Opening the car already turned out to be a problem – the driver’s key lock (central key) wasn’t working. More specifically: worked directly “opposite”. But, as far as I know, it is a normal practice in USA – if the car has been totalized, nobody cares – if it’s not possible to open it in a normal way, the lock is broken, and that’s it.

P.S. later I found out the problem appeared (re-appeared), when somebody tried to open the locked door in a very energic way.

The car starts, the engine works more or less satisfactory. Sometimes some misfire, but – I’ve seen cases much worse. It is interesting when slightly pressing the accelerator pedal, in KOMBI the DSC and ABS symbol error icons light up, but, when the pedal is released, after several seconds they disappear.

MDS80 DME live data indicate strange heating of the control probes. After correct pre-heat and finished warm-up (the probes are being heated according to map with PWM around 45 .. 60 %), time after time the heating increases to 99 % for a moment. It’s not a good sign. It’s typical behavior of DME, which software has been “upgraded”. In this case, it looked as an interrupted procedure of data proceeding of control probes (DME gets information, that control probes are actually not heated, accordingly – the heating has to be restored, no data analysis has to be performed). In which case, such interference could be done? For example – to avoid error messages regarding the performance of the CO catalytic converters! Of course, I can not claim by 100 % exactly the cause in this case, but the possibility is above 90 % in my opinion.

Voltage readings of control probes itself doesn’t match the warming-up strategy (for a long time, their max voltage was decreased, which confirms their management/heating strategies are stopped) – one more suspicious symptom.

Basic list of DME error messages – empty. Info list: empty. However in History list:

Several pages with the same error message, the same mileage! DME doesn’t register the error messages in such a way! Yes, it’s a typical behavious or MSD, if the mileage has been modified. Then suddenly, odometer indications of the old error messages coincide with the actual mileage (because actually, the mileage was higher).

And one more interesting thing – even after repeated error message regarding electrical fan, no other old error messages! Obviously, somebody has made an effort to make sure, that the error messages cannot be read.

The engine has not confirmed offset type LTFT. I checked (to be 100 % sure) both with INPA and ISTA D.

A typical cause of such a problem – significantly different (changing at each driving session) conditions. Respectively – one time in idle one correction is required, on the other time – another correction is needed. Tipical causes of the problem: sucking of air. Quite an unpleasant defect, because it’s sporadic, it can appear only for the cold engine (when pipes, CCV membrane get harder).

But most interesting  – not taking in the account to unconfirmed offset LTFT for a long time, there are ZERO error messages in DME error message memory!

I checked the misfire counters of cylinders:

Here, cylinder No.3 has problems. My attention was drawn not by 2 events in the current session, but one unit in long-term counter. It means during previous sessions, the average number of misfires has been in tenths of events. Taking in account, that other cylinders are “clean”, mechanical efficiency of cylinders – correct, the conclusion is simple: the ignition coil has to be replaced (or has to be switched by one from neighbor cylinder, to make sure for 100 % the problem is not in a spark plug, for example).

All mentioned above is just an introduction for a more interesting part. My attention was drawn to IBS data. SOH a bit more than ten percent  – correct. A pleasant surprise. But the voltage of the alternator – that was completely incorrect! For example, such a moment:

Inquired voltage: 15.0 V, but real 11.4 V? And – no error messages again?

Short look in the memory of DSC module:

Here – the voltage has been both below 9.0 V and above 18.0 V! Notice regarding overvoltage – even active! And – no error messages in DME error message memory?

I recorded a short video:

as you see, the alternator is not able to maintain required voltage, its “kopie” don’t correspond to ordered 15 (max time) seconds, but – there are no error messages!

Obviously, the alternator loses contact between collector and brushes. Continuous exploitation of the car is dangerous (the electronics of the car can get damaged), so I stopped further check of the electronics.

At first, the alternator has to be repaired, then we can continue to check what is happening with electrical fan, Lambda probes, etc.


In the next part – an overview of the “repair” of the car and an explanation, why DME doesn’t contain the error messages.

I believe everyone knows the basic things of USA car market protection legislation. Cars for export are sold via auctions, in auctions “totalized” vehicles can be sold. It means: the repair of which for one by other reason is not profitable. Yes, I’ve heard stories about “only slightly” hit cars, but – reality is not so sunny.

The exact car. When opening the hood, we see:

The cover of the engine is broken. The air collector – can’t be found.

Oil cooler pipe – almost foreclosed, significantly damaged. The pipe to the air filter can be seen.

And it is broken – it falls off from the first touch.

Engine support elements as if are not damaged, but without more serious inspection I can not claim for 100 % they are not “glued together” in place, which can not be seen from the top.

After the accident, the following details have been replaced: both front wings and the hood cover. Quality of repair – miserable. See some pictures without special comments.

The difference between the gaps – at least 2 times!

Each screw – different! It looks they are collected from trash! In the last image you can see Torx screws have been screwed, using pipe wrench or pliers!!! Something like that I see for the first time!

Even the rope is replaced by second-hand one!

It could be some parts are missing. We can see the tire from the engine room!

And yes, previously the car has had the adaptive bi-xenon, but now it has much cheaper and more simple lights…


After performing the diagnostics, the owner of the car got in touch with me. Here are the pictures how the car looked like after driving “underneath the truck”.

And here, the SRS also had worked:

How do you think – is the SRS restored? I didn’t even check, but I’m sure – it’s NOT!

Does the AC of the car works? And how do you think?

Does the working electrical fan is installed?

If we judge from “quality” of repair… I have no illusions.


Why the DME has no error messages? To certify the car it has to be without error messages (for example, regarding the exhaust gasses/system). Said – done! No errors! As there is no error messages regarding SRS.

It’s very possible the non-airtightness of the intake manifold (and problems with LTFT) also are the consequences of the crash. It’s completely clear – nobody, who performed the repair, took care the engine would work correctly.

Finally – note: I’ve heard (already) in Latvia, there have been cases when Insurance companies refused to pay insurance reward for “restored” cars, who previously have been “totalized”.

Yes, I believe, immediately someone will oppose “the car was live, so they have to pay”. Of course, everyone has his rights to go to court. If desired.

Summarizing the seen – the car is a wreck in the classical understanding of the word. It will cost several thousands of EUR to get it in order.


And, in a desert: in the moment of a crash, the car has had a mileage of 127 K.

Only? So my theory regarding changed milage is wrong?

Hmmm… It looks in the Year 2012, the car (for at least one time) has started a new life! Then suddenly the mileage is untypically high (much higher than previously)… What is the true “picture”? Who knows…

As we see, around Year 2013/2014 the average mileage during year was around 40’000 km (in that year the owner of the car has changed, and the new owner was driving more than previous)

Instead, after the Year 2015 (when last data are available) – below 15’000 km/year. Really?