W211 Sometimes will not turn over

[johnmowcop]

Hello, Advice please.
W211 2008 E class 280 diesel. Generally put the key in, turn and engine turns over and starts, as it should. Sometimes, three times in last two days, same as above but the engine will not turn over. Try repeatedly, say after twenty or more attempts it turns over and starts. Today same, drove home, twenty miles, stop it in the drive. Try again, starts no problem.
Any pointers please or do I need a diagnostic check.
JohnT

 

[Wighty]

Hello, Advice please.
W211 2008 E class 280 diesel. Generally put the key in, turn and engine turns over and starts, as it should. Sometimes, three times in last two days, same as above but the engine will not turn over. Try repeatedly, say after twenty or more attempts it turns over and starts. Today same, drove home, twenty miles, stop it in the drive. Try again, starts no problem.
Any pointers please or do I need a diagnostic check.
JohnT

Yes i diagnostic check would be the best place to start . After all it may be more than one problem going on .

 

[mercmancdi]

Hello, Advice please.
W211 2008 E class 280 diesel. Generally put the key in, turn and engine turns over and starts, as it should. Sometimes, three times in last two days, same as above but the engine will not turn over. Try repeatedly, say after twenty or more attempts it turns over and starts. Today same, drove home, twenty miles, stop it in the drive. Try again, starts no problem.
Any pointers please or do I need a diagnostic check.
JohnT

I would take really cheap stab at sticking new battery in key prob CR2025 , if you could hold key and while pushing lock button take photo of end of key with mobile you should see a red dot in photo if key is good , you can’t see the dot without taking photo it’s not visible .

 

[M80]

Starter relay seems like a good place to start.

 

[MercM2Mb]

Happens to mine as well (2008 e220). Best solution is to wait for several seconds to a minute (once) for car to respond! I did not check or report to dealer as the car always wakes up on second or 3rd attempt at most. Not key battery related I think. My theory for my car is that it may be caused by interference in communication between immobiliser in keyfob and car (rfdi tech?) or related mulfunction. Car manual says strong wifi/ electromagnetic signals can cause this _ ( esp.true when arriving or leaving places where your mobile tries to connect to a wifi spot. Eg home!) Newer cars have even a special slot to position the key in such an event to start the car (since keys are now not inserted in the st. Wheel.)

Is the car starter battery ok?

 

[johnmowcop]

Battery is new.
Both at work and home there is good Wi-Fi signal and car fairly close.

 

[johnmowcop]

I would take really cheap stab at sticking new battery in key prob CR2025 , if you could hold key and while pushing lock button take photo of end of key with mobile you should see a red dot in photo if key is good , you can’t see the dot without taking photo it’s not visible .

I tried both keys, same result. I can lock and unlock from a distance, forty feet or so. I would gues fob batteries are ok but I will change them just in case.

 

[Wighty]

I tried both keys, same result. I can lock and unlock from a distance, forty feet or so. I would gues fob batteries are ok but I will change them just in case.

I didn’t think that the battery in the key is used to start the car , just to open it ?

 

[Blobcat]

I didn’t think that the battery in the key is used to start the car , just to open it ?

It’s not… there’s an inductive coil in the binnacle that reads the immobiliser chip.

EIS switch failing isn’t uncommon on this forum

 

[johnmowcop]

After a bit of messing around I got at the batteries, different technique than my C class fob. There are two batteries, both CR 2025, I will replace tomorrow and report back.
coincidentally,I just went and tried it, started straightaway.
What is EIS switch, would that show up on diagnostic ifI finish up with that route.
johnT

 

[Blobcat]

After a bit of messing around I got at the batteries, different technique than my C class fob. There are two batteries, both CR 2025, I will replace tomorrow and report back.
coincidentally,I just went and tried it, started straightaway.
What is EIS switch, would that show up on diagnostic ifI finish up with that route.
johnT

EIS is the ignition switch in the steering binnacle, it should accept the key and allow starting.

 

[Wighty]

After a bit of messing around I got at the batteries, different technique than my C class fob. There are two batteries, both CR 2025, I will replace tomorrow and report back.
coincidentally,I just went and tried it, started straightaway.
What is EIS switch, would that show up on diagnostic ifI finish up with that route.
johnT

You don’t have a lot of other keys hanging on the car key do you ? The weight can prevent proper key identification and starting .

 

[johnmowcop]

EIS is the ignition switch in the steering binnacle, it should accept the key and allow starting.

Is it a hard wired recognition system or does it rely on some kind of proximity handshake. Reason for asking is another time it would not start straight away was when parked at a level crossing waiting for a train to pass through. I had switched the engine off until it went past, it didn’t start/turnover straight away. As well as the overhead electric train cables I was parked near to a large electric type container that I assume holds high voltage and signalling equipment. Surely the key fobs are designed to accommodate that scenario.

 

[mercmancdi]

Does ignition turn on every time or is it dead no lights. Any possibility it’s your ignition lock barrel thats faulty. Thought this would show up on a reader though.

 

[Blobcat]

Is it a hard wired recognition system or does it rely on some kind of proximity handshake. Reason for asking is another time it would not start straight away was when parked at a level crossing waiting for a train to pass through. I had switched the engine off until it went past, it didn’t start/turnover straight away. As well as the overhead electric train cables I was parked near to a large electric type container that I assume holds high voltage and signalling equipment. Surely the key fobs are designed to accommodate that scenario.

It’s the handshake between the key and the car - please have a search on here as many threads on EIS issues.

 

[ajlsl600]

Check all ur earth's, also a bad segment, or segments on starter armature can cause this. Check ur ignition first (unlikely to get dirty doin that) have codes read, historic ref ignition as sometimes, it seems ur fault don't exist.

 

[mercmancdi]

Just putting this in. /
A EIS module that has become defective could also be a reason for a “Mercedes turn key nothing happens” situation. Many car owners complain that their vehicle starts fine on mild or hot days, but not on cold days. This could seem unusual, but it is a common occurrence. Processors are soldered on the circuit board of the EIS, and in many cases, the processor's connections are poor or the processor itself is faulty.

If you are experiencing this problem, you will need to install a new / virgin EIS. Since the EIS must be coupled / married to the car using Mercedes-Benz Star Diagnostic Software, you cannot mount a used unit.

It's likely that the car won't start because of the key. The key will unlock the doors but not start the vehicle. The transponder coil wires can become detached and need to be resoldered in certain situations, or the key's processor may be faulty. In this case, the easiest solution is to order a new key from a Mercedes-Benz dealer.

 

[johnmowcop]

Just putting this in. /
A EIS module that has become defective could also be a reason for a “Mercedes turn key nothing happens” situation. Many car owners complain that their vehicle starts fine on mild or hot days, but not on cold days. This could seem unusual, but it is a common occurrence. Processors are soldered on the circuit board of the EIS, and in many cases, the processor's connections are poor or the processor itself is faulty.

If you are experiencing this problem, you will need to install a new / virgin EIS. Since the EIS must be coupled / married to the car using Mercedes-Benz Star Diagnostic Software, you cannot mount a used unit.

It's likely that the car won't start because of the key. The key will unlock the doors but not start the vehicle. The transponder coil wires can become detached and need to be resoldered in certain situations, or the key's processor may be faulty. In this case, the easiest solution is to order a new key from a Mercedes-Benz dealer.

Thank you for the detailed description. I doubt if it is the key, Ihave two keys and the issue is the same with both keys. Just put new batteries in one key and no change, the problem still exists. Next up is to have diagnostics done I presume.

 

[supernoodle]

A good write up of the system

WIS 80.57 Drive Authorization System - W220 S-Class Encyclopedia

w220.wiki

 

[pgh13]

Maybe a bit left field, but have you noticed if the gear indicator on the dashboard is doing anything silly? Just had problems with the gear selector module giving dodgy info on the gear selector position. The original selector, when at fault, blanked the gear and sport/comfort indication on the speedo.
The new S/H replacement behaved for a couple of days but then started to do random things...e.g. turn the key, it showed P but about 1/2 second later it changed to R, stopping the engine from turning over