Grifff

Hi all,

Just picked up a 2013 E220 W212 and noticed an issue with the stop start. The previous owner didn’t like it so always turn off the eco button.

the ECO logo on the instruments comes up and goes green fine. I will pull up to come lights and when my foot is on the brake it cuts off for stop/start as expected. But after 2/3 seconds without me moving a muscle kticks back in and the car tries to lunges forward quite heavily.

anyone seen this before or have any idea?

Thanks, Griff

whoover

It could be the battery is tired. The computer restarts the engine if voltage is below a certain threshold. Or if it's hot out, the AC will turn it back on to keep the compressor running. Lots of reasons to not like it.

kajtek1

The system needs to meet up to 12 parameters to kick-in. Usually it is battery going bad, but with 2 batteries changing parts without proper scanning can turn costly.

Grifff

Thanks for the quick replies, will get a battery tester on the two of them after just seeing the price of a new main battery 😳

kajtek1

I bought trunk battery just weeks ago at FCP Euro.
They have been slightly more expensive than other on line places, but give you lifetime warranty.
Since those batteries die in 2-3 years, I figure out I can use it at least twice.

Grifff

What is the model name or spec of the trunk battery?

dbldpr

Unbolt the trunk battery and bring into pep boys and they will get you an equivalent battery. Note there is also a fuse in the trunk that controls the eco start stop.

Grifff

Thanks dbldpr, I presume the fuse should be ok or if it had blown ECO wouldn't work at all right? Can you pull this fuse to disable it permanently?

dbldpr

Yes from what I have read on the forum. The fuse is only for the eco start stop. I have the module to disconnect it but later in the forum they posted how to disable it with the fuse. I do not know which one but if you check the forum you should be able to find it.

whoover

And as has been noted, there are a dozen different reasons the engine management system will not let the engine stay off. A weak battery is one but there are lots of other possibilities. Throwing parts at it can get pricey. As was also noted above, it really makes sense to read the code(s) that are stored when the system forces the engine back on. That way you'll know what's up rather than guessing. A decent independent shop will be able to pinpoint the issue in minutes.

DFWdude

A penney drops here. Eco Stop shuts off my engine at the traffic stop light, as designed. But after 20-30-seconds or so, the engine restarts on its own. (My foot is still on the brake) I thought this normal (30-secs of gas saved is the intent), although the red traffic light has another minute to go before turning green.

Are you saying that uncommanded engine restarting indicates a fault that needs to be investigated? I want to have my Aux battery tested before the warranty expires, and this might be a good reason to ask for it.

whoover

Yes, it should stay off longer than 30 seconds unless you have the AC set low and it's hot out, in which case the system restarts it for the compressor. You can tell if that's the cause by raising the AC temp setting at the next light. Otherwise, you should have them read the codes.

My car did that (20-30 seconds) from when I picked it up new. It was only after it was in for it's 2K rear-end service that I realized it wasn't normal, because the loaner's engine stayed off far longer. I called it in to the SA and they discovered a bad battery.

Grifff

Thanks guys I will defiantly get the codes read, did the bad battery throw up a fault code? Mine seems to last for 2 seconds or so before it kicks in and tries to lunge forward.

raja777m

AUX-14 is the model number from AutoZone.

whoover

The engine management controller logs the reason it overrides eco stop. It's not the battery throwing a code per se, but it's an entry that the engine was force restarted due to low voltage.

kajtek1

$150 buys you MB-oriented scanner, what is about what dealers charge for 1-time troubleshooting.
There is no good reason to not own one and stop wasting forum time on something you don't want to check
https://www.fcpeuro.com/products/mer...mer-0009829308 this is the aux battery for ECO option. As I said, you can find it cheaper, but not with lifetime warranty. Than I think FCP runs Pozi scheme, so I hope to get my replacement before it collapse.