2019 Merc B200 - different water temperature readings?
Discussion
Interesting one here.
SWMBO has recently got a new (to us) car - a 2019 B200.
Still getting use to the 7 speed DCT (all our previous cars have been manuals etc) - but I did notice there is a funky engine display setting you can get on the centre display unit - which appears to show engine HP, torque in NM, water temp, oil temp, battery voltage and boost pressure.
First off = love that there is a battery V meter and oil temp gauge
However - on inspection the boost /charge air pressure never shows any reading (its a 1.33 Turbo - so there really should be some boost pressure), and the water temp gauge on the engine display appears to disagree with the water temp reading on the main drivers display...
Which feels a little odd -how can there be two different readings for water temp?
Pictures below.
The car had not been driven that long and was stationary at idle- so the lowish water temperature is plausible...:
However the engine "water temp" reading was consistently lower than the temp on he main waters display when driving.
Central engine display - what I assume is water temp far right showing c50 degC
Charge air pressure never registered anything at all whilst driving
And main drivers display - showing c88 degC on the temp gauge
Thoughts?- is this as it should be? - are the water temp readings actually different reading (eg water temp at radiator exit/engine inlet, and engine outlet/rad inlet could plausibly be different by 30-40 degrees.....
Ans whats with the charge air pressure - surely that should rise when on boost (it never registered anything whilst driving)
Appreciate thoughts - thank you.
SWMBO has recently got a new (to us) car - a 2019 B200.
Still getting use to the 7 speed DCT (all our previous cars have been manuals etc) - but I did notice there is a funky engine display setting you can get on the centre display unit - which appears to show engine HP, torque in NM, water temp, oil temp, battery voltage and boost pressure.
First off = love that there is a battery V meter and oil temp gauge
However - on inspection the boost /charge air pressure never shows any reading (its a 1.33 Turbo - so there really should be some boost pressure), and the water temp gauge on the engine display appears to disagree with the water temp reading on the main drivers display...
Which feels a little odd -how can there be two different readings for water temp?
Pictures below.
The car had not been driven that long and was stationary at idle- so the lowish water temperature is plausible...:
However the engine "water temp" reading was consistently lower than the temp on he main waters display when driving.
Central engine display - what I assume is water temp far right showing c50 degC
Charge air pressure never registered anything at all whilst driving
And main drivers display - showing c88 degC on the temp gauge
Thoughts?- is this as it should be? - are the water temp readings actually different reading (eg water temp at radiator exit/engine inlet, and engine outlet/rad inlet could plausibly be different by 30-40 degrees.....
Ans whats with the charge air pressure - surely that should rise when on boost (it never registered anything whilst driving)
Appreciate thoughts - thank you.
Ok- to answer my own thread - it would appear some folks believe the temp on the left is the gearbox transmission oil temp - based on this thread (https://www.aclassclub.co.uk/threads/mbux-engine-data-display-what-do-they-all-mean.24649/)
Doesn't explain why the charge air pressure reading never reads anything though
Doesn't explain why the charge air pressure reading never reads anything though
Yep, you have answered your own thread! 
Going from left to right you have: Gearbox fluid temp, oil temp and then coolant temp in the drivers display.
As you say though that doesn't explain why the charge pressure isn't showing... a few things to try:
- Firstly, does the car feel turbocharged? The 200 is an amazingly peppy engine for only 1.3l and therefore has almost 80s style turbo lag! You would notice if the turbo wasn't providing pressure. I'd suggest giving it a good thrash at some point and see what you think. (It will drop a few gears to help and sounds a little thrashy towards the top end)
- Secondly, does changing the pressure unit to PSI or Bar change anything. This should be possible in the settings, system, units menu.
If it's still not reading anything then I'd suggest getting it looked at by wherever you bought it from. It would likely just be a sensor if it's still providing boost. The car would likely go into limp mode if it felt there was an issue though...
How are you finding it other than this? The B Class is a massively underrated Merc in my opinion. I always enjoy driving them way more than I expect to!
Any other questions let me know! BB
Going from left to right you have: Gearbox fluid temp, oil temp and then coolant temp in the drivers display.
As you say though that doesn't explain why the charge pressure isn't showing... a few things to try:
- Firstly, does the car feel turbocharged? The 200 is an amazingly peppy engine for only 1.3l and therefore has almost 80s style turbo lag! You would notice if the turbo wasn't providing pressure. I'd suggest giving it a good thrash at some point and see what you think. (It will drop a few gears to help and sounds a little thrashy towards the top end)
- Secondly, does changing the pressure unit to PSI or Bar change anything. This should be possible in the settings, system, units menu.
If it's still not reading anything then I'd suggest getting it looked at by wherever you bought it from. It would likely just be a sensor if it's still providing boost. The car would likely go into limp mode if it felt there was an issue though...
How are you finding it other than this? The B Class is a massively underrated Merc in my opinion. I always enjoy driving them way more than I expect to!
Any other questions let me know! BB
Hi - thanks BB.
The turbo is definitely working.
Its pretty nippy - on paper its as nippy as my 1980's mk2 golf GTI was 0-60, and when coupled with the slightly aggressive throttle response, automatic DCT gearbox, and light controls it feels pretty nippy and at least as comparable.
Definitely not a 1.33L petrol with no boost- would feel very very flat it if was I would expect.
Which does suggest a sensor issue - however then I would expect to see engine faults/limp home mode - which I can see none.
I do have an OBD scanner - which I might plug in as that should give a boost reading from the ECU (it did on my A6 and S4 - so presume it will also works for Mercs.)
So far the car is good. Big jump in tech from our previously pre 2010 cars without all the driver assists interventions.
Lane departure has not felt intrusive so far - which is good - I was worried about this one. Simililarly car is complaining about proximity to car in front "most of the time" on the motorway when in traffic - but its not tried to intervene yet.
Fuel economy is good. Interior space (especially headroom) is good - much better than the GLA, Q3, A3 etc we also looked at.
Fuel economy is pretty good so far.
Just not got used to the gear box - at the moment feels slightly binary in terms of "trundling along" versus going for it accelerating - not learned yet to smoothly and progressively increase acceleration yet - but I suspect thats a case of learning to work with the gearbox.
Find ourselves needing to use the brake much more - it does not want to do gradual engine braking - even when not in eco mode. Using the flappy paddles to force it into lower gears to encourage engine braking works a bit - but even then the 1.33 doesn't give that much engine braking (wife and I both used to much bigger engined cars).
Finally - not figured out how to actually turn the car "off" yet.. as in once engine is off, whatever I do leaves the dashboard lit with lights - music going, etc - so end up walking away, locking it - and hoping it turns itself off fully...
....again part of the learning process - only driven it a couple of times so far...
The turbo is definitely working.
Its pretty nippy - on paper its as nippy as my 1980's mk2 golf GTI was 0-60, and when coupled with the slightly aggressive throttle response, automatic DCT gearbox, and light controls it feels pretty nippy and at least as comparable.
Definitely not a 1.33L petrol with no boost- would feel very very flat it if was I would expect.
Which does suggest a sensor issue - however then I would expect to see engine faults/limp home mode - which I can see none.
I do have an OBD scanner - which I might plug in as that should give a boost reading from the ECU (it did on my A6 and S4 - so presume it will also works for Mercs.)
So far the car is good. Big jump in tech from our previously pre 2010 cars without all the driver assists interventions.
Lane departure has not felt intrusive so far - which is good - I was worried about this one. Simililarly car is complaining about proximity to car in front "most of the time" on the motorway when in traffic - but its not tried to intervene yet.
Fuel economy is good. Interior space (especially headroom) is good - much better than the GLA, Q3, A3 etc we also looked at.
Fuel economy is pretty good so far.
Just not got used to the gear box - at the moment feels slightly binary in terms of "trundling along" versus going for it accelerating - not learned yet to smoothly and progressively increase acceleration yet - but I suspect thats a case of learning to work with the gearbox.
Find ourselves needing to use the brake much more - it does not want to do gradual engine braking - even when not in eco mode. Using the flappy paddles to force it into lower gears to encourage engine braking works a bit - but even then the 1.33 doesn't give that much engine braking (wife and I both used to much bigger engined cars).
Finally - not figured out how to actually turn the car "off" yet.. as in once engine is off, whatever I do leaves the dashboard lit with lights - music going, etc - so end up walking away, locking it - and hoping it turns itself off fully...
....again part of the learning process - only driven it a couple of times so far...
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