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Hey whats up? I’m excited to join this forum. I made the best decision recently and I switched from Bmw to Mercedes. The best or nothing - I can tell now. ok but here is the issue, my start/stop function is not working from the day i bought the car. I’m not complaining, never liked that feature but I just want to know what is wrong. Ok here are the details: In my dashboard, I neither have the yellow “A” nor the green “A”. I switched from comfort to eco, also tried to select auto start/stop in the individual drive mode. Nothing! the button close to the arm rest is green though. Any suggestions? Weak battery or something else? Do I need to worry? My car is a 2017 C300 sedan base
Did you buy the car from a private party? Many owners find start/stop annoying and either code it permanently off or pull the battery sensor connector to disable it. Contact the seller and ask. If you bought it from a dealer, they can scan the coding configuration and reset it if that's the problem.
And there are some prerequisites for it to operate, such as the engine warming up and the battery being sufficiently charged.
It was private party. It was an older woman, the car had 2 owners before me. Maybe the one before did something because she didn’t seem very knowledgeable.
Would this show up as an error code? I don’t have any messages on the dash.
Also it is my first time owning a Mercedes, the looking horn sound sounds a little bit like a small fart I don’t know if it should be a loud sound? Maybe the battery is weak??? Everything else is working though.
do you recommend any obd app that I can use for coding. Like I said before I jumped ship from BMW and I used bimmerlink. Is there something similar for Mercedes?
a cheap non-AGM battery or weak battery will disabled eco start/stop.
i used to have a non-AGM battery, it only works for like 2 months.
now i replaced it with AGM battery, 1 year later eco start/stop still working.
It was private party. It was an older woman, the car had 2 owners before me. Maybe the one before did something because she didn’t seem very knowledgeable.
Would this show up as an error code? I don’t have any messages on the dash.
Also it is my first time owning a Mercedes, the looking horn sound sounds a little bit like a small fart I don’t know if it should be a loud sound? Maybe the battery is weak??? Everything else is working though.
do you recommend any obd app that I can use for coding. Like I said before I jumped ship from BMW and I used bimmerlink. Is there something similar for Mercedes?
Things that can disable start/stop:
1. Weak battery or underperforming alternator (check with multimeter / battery load tester)
2. Auxillary battery issue (harder to diagnose, usually triggers a dash message when failing)
3. Unplugged voltage sense connector at main battery (easy to check)
4. Coding changes (I'd be surprised if anyone coded it permanently off, more common is modify it to remember last state)
As for your last Q, ODB2 scanner for general code checks. Xentry is the dealer s/w for in-depth analysis, you can find copies online
Today I went to Mercedes and turned around again after they told me the numbers. $250 to check if the battery is good and reading the codes and doing diagnostics. I asked how much a new battery cost. $600!!!! So I left lol. I thought at least they would check the battery for free.
anyway, I went to autozone and they checked the battery. Even though my battery was working and starting normal. It was showing bad battery and 90% charge. So I ended up buying a battery from autozone ($250), same specs as the oem battery.
And it fixed the start/stop function!!! Now I can finally turn it off manually again haha.
Today I went to Mercedes and turned around again after they told me the numbers. $250 to check if the battery is good and reading the codes and doing diagnostics. I asked how much a new battery cost. $600!!!! So I left lol. I thought at least they would check the battery for free.
anyway, I went to autozone and they checked the battery. Even though my battery was working and starting normal. It was showing bad battery and 90% charge. So I ended up buying a battery from autozone ($250), same specs as the oem battery.
And it fixed the start/stop function!!! Now I can finally turn it off manually again haha.
Auto start/stop requires a collection of prerequisite conditions for operation, one of which is battery charge level. A sensor on the battery's negative terminal determines if the battery can sustain engine starting. If the battery sensor reports a heavy charging current, s/s is disabled. Disconnecting the sensor is how I intentionally disabled s/s, until recently coding it off.
Glad you got a new battery at a reasonable price.
how much it costs? can we code it to remember last state?
There are some other recent forum posts that describe doing this with a Launch OBD scanner. I find s/s so annoying I coded it off rather than last state.
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Dash lights only show if you need to DO something to comply with emissions (i.e., Check Engine) or be safe (brake warning, tire pressure, etc.). You do not get a light every time something is whacky.
EVERY Mercedes owner needs to have a Mercedes-specific scanner unless they want to pay $250 to get their battery checked. The very popular and affordable scanner is the LAUNCH Creader Elite 2.0 BENZ, about $160 on Amazon. Get one!
Get this and test your battery yourself.
Finally, check your brake fluid if you have not changed it in the last two years.
for the Launch scanner and most any battery tester (I have a Topdon BT300). Not so sure about the brake fluid tester. The one I acquired could differentiate new brake fluid from water, but seemed not so accurate in measuring 1%, 2% and 3% water dilutions of brake fluid. Oh well -- batteries and brake fluid are cheap and easy enough to replace preemptively. CELs deserve investigation with a scanner.
It's a little bit technical and not without risk, as you're reprogramming a module. You will also need to purchase a passthru adapter, but that is worthwhile as any advanced analysis/coding requires it.
Dash lights only show if you need to DO something to comply with emissions (i.e., Check Engine) or be safe (brake warning, tire pressure, etc.). You do not get a light every time something is whacky.
EVERY Mercedes owner needs to have a Mercedes-specific scanner unless they want to pay $250 to get their battery checked. The very popular and affordable scanner is the LAUNCH Creader Elite 2.0 BENZ, about $160 on Amazon. Get one!
Get this and test your battery yourself.
Finally, check your brake fluid if you have not changed it in the last two years.
As stated above, many stores test the battery for free.
or do it like me.
i keep using the battery until i need to jump start the car.
Same, got that yellow message saying that keep the car running etc. couple of months ago. Now I charge the battery once a month with a separate charged and haven't seen the error anymore. Also will use the battery until it dies completely on me, hopefully in my garage.
03-30-2024, 06:03 PM
I don’t know if it should be a loud sound? Maybe the battery is weak??? Everything else is working though.
