Key Fob Problems

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pcthrillrider

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Feb 28, 2015
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Location
chelmsford essex
Car
2017 C220 CDI 4MATIC AMG LINE PREMIUM
Mercedes W204 2012 220cdi got problems with key fob,the distance from car the fob works is very close to car now, and also when i insert fob in ignition the steering lock releases
slow. i have replaced the battery in fob still no change. anf ideas anyone?
 
i dont have a spare, after doing some google search it seems to be the ESL motor failure


Slow unlocking of the steering on it's own would suggest imminent ESL motor failure but if that was the only fault there would be no impact on the operational distance to unlock the car. My key fob battery is well in excess of 5 years old and it still operates from inside the house when the car is parked outside.
 
Press lock and hold , press and hold unlock until you see the red led flashing . Try that.
 
Slow unlocking of the steering on it's own would suggest imminent ESL motor failure but if that was the only fault there would be no impact on the operational distance to unlock the car. My key fob battery is well in excess of 5 years old and it still operates from inside the house when the car is parked outside.
the range nows is good, but the volts across the battery under bonnet is only 12.33 volts, could it be a battery problem? 8 years old now the battery
 
The battery may be shot but not necessarily just because it's 8 years old. I'd fully charge it first and see how it goes. Expect it to take several hours as 12.33 volts under no load is barely above 50% charged.

Even if it turns out the battery is on it's last legs, getting up to full charge may make your original ESL problem go away which I expect would be a relief.
 
My problem is the key unlocks the car (all doors) when turned in the drivers side door. I do this because the buttons don't work even after resynchronising as per the manual.
I've ordered new Varta 2025 batteries, which I'll get next week. They are the same as the old ones (7 years old).
All was good until the wife's key died a while back. She asked if my key batteries would work and it didn't and when I put mine back in, mine didn't work either, so I'm hoping it is only the batteries.
I'll know next week. I'll come back if it doesn't work.
 
The battery may be shot but not necessarily just because it's 8 years old. I'd fully charge it first and see how it goes. Expect it to take several hours as 12.33 volts under no load is barely above 50% charged.

Even if it turns out the battery is on it's last legs, getting up to full charge may make your original ESL problem go away which I expect would be a relief.
had the 2 battery's tested today aux battery ok but engine one is at 51% and told to replace maybe this will sort the esl problem too!
 
had the 2 battery's tested today aux battery ok but engine one is at 51% and told to replace maybe this will sort the esl problem too!


We already knew it was only approx. 50 % charged so did you fully charge it before having it tested. That won't necessarily give it a clean bill of health but it will give it the best shot at a load test.
 
We already knew it was only approx. 50 % charged so did you fully charge it before having it tested. That won't necessarily give it a clean bill of health but it will give it the best shot at a load test.
not the charge, the cranking amp's battery is rated at 800amp's only giving 471 amps
 
I know the test figure wasn't the state of charge but you get the best cranking amps from a fully charged battery even if the tester is able to compensate for a low state of charge. Bear in mind that battery testers don;t actually measure the cranking amps refereed to because to do that they would have to freeze the battery. The load test estimates the cold cranking amps from the what the battery can do at normal ambient temperature. 471 amps is more than enough to start your car though.

If the ESL issue was being be caused by the battery it would have been the low voltage rather than it's ability to produce starting amps. It may still be that the battery needs to be replaced but I would always give it a best shot by fully charging it first.

Keeping lead acid batteries fully charged is the No 1 rule for long life and in my book any debate about what condition a battery is in becomes a bit pointless until full charge has been achieved.
 

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