Technical Malfunctioning milometer on Marea

[MVirta]

I filled up my Marea's tank today. I have an Excel sheel which calculates period and total fuel consumption. I filled in the data containing the date, mileage and fuel amount, and let the software (which in fact is OpenOffice) calculate the figures.

The period comsumption was huge, so I realised something is wrong.

Here are some data:

24.1. 120.060 km
22.2. 120.660 km (45,0 litres)
8.4. 120.697 km (44,03 litres)

I had a MOT check on 28.3. where the mileage was 120.643 km.

It seems that from 24.1. to 22.2. everything is correct. From 22.2. to 8.4. something strange had happened. I have (in reality) driven about 600 km, but the mileage has increased only 37 km.

When I had the MOT check, the mileage was 17 km less than in February. How could this be possible? The MOT man may have read the milometer incorrectly, but too a low increase between the two refuellings is a fact.

Does anyone know what can cause this? The tripmeter seems to function correctly, however.

 

[Neverth]

mk1/mk2? mechanical display or digital.

Speedo working?

Check if ECU has the right milage and increments right -> problem with dash unit.

 

[MVirta]

It's digital. Speedo is working, and also the tripmeter.

Check if ECU has the right milage and increments right

How is this done?

 

[Neverth]

The way you would usually read stuff from ECU.
Multiecuscan/some code reader.

Might be the dash unit, bad solderjoint or something.
Give it a good slap on top of the dash and see if it breaks or fixes itself.

 

[MVirta]

The milometer has been functioning normally after the latest refuelling. When I fed the data into the sheet (on Tuesday) I didn't know that yet.


Now I am getting to figure this out. Everything indicates that the fault is the OBD test carried out in the MOT check. Connecting the device to the ECU had somehow interferred it. There is no other reasonable explanation.


I sent an email to the person in charge of the MOT station and explained the issue to him. Let's see what he will answer.