Odometer displays and keeps the record of the mileage of the car. Modifying the odometer – very common in the market if used vehicles. BMW is not an exception. Typically the readings of the odometer are reduced to increase the value of the car, to make it more “fresh”. The increasing of the mileage is much rarer. It is chosen by owners of the car in the countries, where the taxes get lower when the mileage increases. This is also popular with commercial vehicles (to steal the fuel).
Recently my friend checked BMW F-series cars of the local market via BMW Online system – it turned out, that 42 of 44 cars of ones for sale (or around 95 %) have significantly modified odometer readings.
In this entry about more popular – reducing the mileage of the vehicle. And just about that, how it affects DME diagnostic. Of course, the manufacturer doesn’t give any information, how they fight to modify of the odometer, so – we can only follow the inadvertent signs. Obviously, both Siemens (MS/MSV/MSD) and Bosch (ME/MEV/MEVD) DME doubles the readings of the odometer in a separate message memory cell. If by some reason (some unallowed modifications, etc.) the value of the odometer is lower than the previously recorded reading, DME stops to record the readings of the odometer in the error message attributes. When checking the output of the error message list, all error messages are displayed by the current odometer reading.
Even more interesting situation is with sporadic error messages and History list for Siemens DME. In a regular situation, for the record of sporadic error messages (Error list of Bosch DME and Freeze-frame of Siemens DME) and Siemens History list records the reading of first, one-before-last and last event. As you can guess, in case of a modified odometer, all readings will be identical – the information regarding true mileage will not be available.
Here, DME error message has 12 (!) error messages recorded. Odometer reading for all of them – identical. Odometer reading for all sporadic error messages – identical. For your attention, I printed out only first 4 pages – believe me, the situation is identical for all other error messages too. Pay attention – other parameters of each individual case of the same error message are different. For example the misfire problem of the 3-rd cylinder:
Yes, we can assume, that the onboard voltage and RPM can change in a very short moment, but the temperature of the engine is significantly different. The engine has huge thermal inertia – for its temperature to change for 10 oC, quite a long time has to pass. So, judging by the RPM – the car was driving, the temperature has changed significantly, but the mileage – haven’t? Additionally, nor Siemens no Bosch don’t register the sporadic events with an intensity “one record in one second”. I have no slightest doubt, that the odometer readings are not recorded!
Here, the printout of the History list of MSD81 DME. How is that possible, that the reading of first, one-before-last and last event are identical? And for all error messages (again) only one (a current) mileage is recorded?
In all cases, after detecting such symptoms and performing a deeper investigation, I have identified the modifying of the odometer. Yes, sometimes there is a situation, when, for example, the DME has been replaced and it’s installed from the other vehicle. But, as when know – DME has to be synchronized with CAS. It’s not a “plug & play” case. Usually – persons, who perform such procedures (they are complicated enough), arrange the proper reading of the odometer in all units. Problems mentioned before, in 99 % of cases, indicate cheap and unprofessional modifying of the odometer in the history of the car.
The true mileage of the car stays on the conscience of the modifier. My job as a diagnostic’s performer is quite burdened with the non-existence of the odometer data. Which error message is recorded when? Is it new or old, recorded before or after the last repair? These are the questions, for which usually is no answer.
Here, how the correct odometer values of Bosch and Siemens DME look-alike: