Update software or not?

[MBYorkie]

Got my 2014 C Class going in to Merc for a passenger airbag recall later this month. I've been reading on various platforms when owners take their car to Merc they stress NOT to do a software update to the dealership. Why? What's wrong with getting the software updated? Asking just in case I should be telling them I don't want it.

 

[BTB 500]

Assuming it's a diesel MB might update the ECU to the bring the exhaust emissions in line with the figures they published for that model (you've probably heard of 'dieselgate'), which could potentially have a small impact on performance and/or economy. Whether you'd ever notice this in the real world is another matter though.

 

[Chrishazle]

A lot of members on here and t'other side have commented that the emissions update had a noticable effect on fuel consumption - in a negtive way. If that is the update, tell them no thanks!!

 

[Mickyh7]

Do a Google first and see if your car is actually affected by Dieselgate. If its not, like mine, then there's nothing to worry about.

 

[MBYorkie]

Pretty sure it is affected by Dieselgate. As I use it for a Taxi, I assume it'll probably have a bigger effect on me. Think I will politely ask them not to do it if they suggest it needs it.
Didn't realise it actually changed how the engine runs, just thought it changed the dash readout to tell what's really happening i.e. the real consumption.

Thanks for the advice.

 

[markjay]

Some members reported that after the "Dieselgate" update, the 7-gear transmission didn't go into the top gear at the UK motorway speed limit (70mph), instead in remained in 6th gear and only went into 7th at around 80mph, which partially explains the poorer fuel consumption, especially if this is the case throughout the rev range, i.e. the car shifts at higher engine revs (presumably to keep the engine at operating temperature).

Members also complained about NOx sensors failing after the update, with some dealers replacing them for free while others did not (not a cheap repair, if you can even get the sensors).

 

[MBYorkie]

Mine is a manual so I'm guessing it would have a different effect.

 

[23 Romeo Tango]

Also discussed here

S204 - Passenger airbag recall | Mercedes News

Just received this:

forums.mbclub.co.uk

 

[TC350]

A lot of members on here and t'other side have commented that the emissions update had a noticable effect on fuel consumption - in a negtive way. If that is the update, tell them no thanks!!

Are those genuine changes to fuel consumption or perceived changes?

Are they accurately determined changes being observed during measurements of fuel usage between top ups recorded against mileage over comparable journeys in comparable conditions? Or are they just mental notes of the on board fuel consumption on different days?

I ask the above because I notice quite significant variations in the indicated fuel consumption of my car from day to day, week to week, and month to month. And that's with a petrol car that hasn't had any software updates.

An earlier comment also makes me wonder whether or not the update changes the algorithm used to display mpg on the various car screens. I've certainly had the impression that there's often a sizeable discrepancy between what different indicators are telling me.

 

[Wearsthefoxhat]

Our 2019 V220 has, since its software update dropped from 38 mpg to 34 mpg on long runs. Around town it is also lower. Cruise control speed needs to be 70 plus for it to go into 9th gear..

 

[ALFAitalia]

That a far bigger drop that I would have thought.....minus 10.5%.....how does burning MORE fuel improve the emissions to the claimed level???

 

[markjay]

That a far bigger drop that I would have thought.....minus 10.5%.....how does burning MORE fuel improve the emissions to the claimed level???

I think it's about not allowing the engine to run cold. Apparently Diesel emissions are higher when the engine isn't running at its optimal operating temperature.

 

[Bellow]

The emission in question is NOx and has been stated umpteen times previously lowering NOx and CO2 output simultaneously isn't possible.
In essence, the update returns the car to an emissions output that enabled the car to be sold but would have been unappealing to the customer as the mpg would be worse.
Two ways to look at it. The cars were sold with inflated mpg figures compared to what they were legally capable of - and are now having to be recalibrated to. Or. that the emissions levels were misrepresented by cheating the testing/homologation process and as such the cars should never have been sold and, had the cheating not occurred, could not have been sold.
Well done UK, you let the manufacturers off the hook while leaving the customers to suffer the consequences.