W202 Year 2000 ignition problem can't start car

[Cw-kid]

Hello

My C230 W202 Year 2000 model has developed a fault where the electronic key stopped turning in the ignition. We have removed the ignition unit where the key goes in and there is a little plastic flap that can be seen inside this is meant to move up and down presumably by the electric coil on the unit.

When in the down position the key cannot be turned, gently prising up this piece of plastic and now the key can be turned and the ignition lights come on but the car will not start.

Would removing the ignition unit trip the immobiliser, does it now need recoding?

When inserting the key I can hear a noise and the steering lock is still released OK the key fob also locks / unlocks the doors OK.

Any thing else to check or try out?

Many thanks

 

[BlackC55]

It sounds like the ignition switch has failed. It needs to go on a Star before you do anything else.

 

[grober]

The ignition key unit on the later W202 models is I believe coded to the engine ECU and immobiliser. If its gone down completely there's no easy fix and you will have to go to MB for new parts. As Olly suggests Star [ in the hands of someone who knows what they are doing] is your first port of call.

 

[Cw-kid]

Hi thanks for the replies.

What's a Star ? Diagnostics machine ?

It seems to have started working again, I took the circuit board out of the key fob this morning to just have a look at the soldering and everything looked fine, so I put the fob back together, I then went to the car which was still in pieces with the ignition hanging out and I inserted the key, this time the key would turn OK and that plastic flap thing inside the ignition switch would lift up in order so you can turn the key, it was not doing that yesterday, I then turned the key all the way and it tried to turn over the engine but the battery was flat.

I put on some jump leads with another car and then it started OK. Its been fine since and I have stopped and started the car several times since.

I just hope its resolved itself and its not an intermittent problem that comes back, fingers crossed.

 

[grober]

STAR is the official MB diagnostic system which can give you live data as well as fault codes. It can access all modern MB car systems whereas OBD code readers, while useful, can only reveal so much.

 

[Cw-kid]

Hi

Just to follow up on this, after taking the ignition unit out that day and having messed about with it and putting it back on the car, it eventually started to work fine again and has done ever since.

Only a few times since I have been unable to turn the key on first try and I find if I remove the key turn the key the other way round and insert it again then the ignition unlocks / starts OK.

All in all very strange and I hope it never happens again as it sounds like an expensive repair.

 

[Cw-kid]

So more than a year later, today the car has done the same thing again and I am unable to start the car. Its been perfectly fine all this time until today. The ignition is not recognising the key and its not making the normal sound of the relay lifting up the little plastic catch thing inside which then allows the key to be turned.

I took it apart again and managed to get the key to turn and the ignition to turn on but the car would still not start or turn over. I then tried to short out the starter motor, this turns the engine over but does not start the car is immobilized.

Also the key fob is no longer locking / opening the doors, tried new batteries.

Just hoping it fixes itself again like last time, when I look at it again tomorrow.

If not I'll have to get the AA to take it to Mercedes, as the steering lock is on and I can't move it.

This could be an expensive fix! Will Merc diagnose the problem for free? and tell me what parts I need and how much for them to recode the key? Or do they charge me to tell me what part I need?

I can fit the new ignition switch myself as its already all taken apart again just need them to tell me what part is actually the problem and how much for them to supply and recode it if need be.

Part number of the ignition unit is 210 545 02 08 Q2

Don't understand how its been fine for well over a year and then just goes again same as before. There were warning signs this week, three times I got in the car this week and turned the key ignition came on OK but then the car wouldn't start on first turn of key. But on each second attempt the car then started fine.

Is there any way to completely by-pass the immobiliser and do away with the bloody thing.

Cheers

 

[Cw-kid]

The only other thing I have done but not recently it was several months ago I removed the alarm siren from the car as it never worked anyway's and I decided to take it off one day and have a look at it, it had the normal issues of the batteries leaking on the to the circuit board and damaging it. I never got round to buying a new siren unit and its been fine for months without it attached.

There is another thread here with the same problem, his solution was:

"I bought a complete set of Key,ECU,ESL,EIS, installed and the car is as good as new."

Also I only have one smart key, my spare key is just a piece of plastic that fits in the ignition and it has the metal blade key in it as well. So I can't test with a spare smart key.

Just taken my smart key apart again and it looks OK, the circuit board and the coil on the end of it, but who knows just by looking at it.

 

[Dec]

The only other thing I have done but not recently it was several months ago I removed the alarm siren from the car as it never worked anyway's and I decided to take it off one day and have a look at it, it had the normal issues of the batteries leaking on the to the circuit board and damaging it. I never got round to buying a new siren unit and its been fine for months without it attached.

There is another thread here with the same problem, his solution was:

"I bought a complete set of Key,ECU,ESL,EIS, installed and the car is as good as new."

Also I only have one smart key, my spare key is just a piece of plastic that fits in the ignition and it has the metal blade key in it as well. So I can't test with a spare smart key.

Just taken my smart key apart again and it looks OK, the circuit board and the coil on the end of it, but who knows just by looking at it.

Is it like the one bottom left in picture?

Dec

Picture source… 2006 C55 leather key fob cover? - MBWorld.org Forums

 

[Cw-kid]

Hi Dec

Yes my spare key is like the one in the bottom left of the picture. My main key is the top left one.

Cheers

 

[Dec]

The alarm has no control over the immobiliser, it is the smart key that releases the immobiliser or the flat key in picture.
The flat button less key will start the car and its metal key blade will open the door / boot, it is an emergency key and is suggested / intended to be carried in your wallet in the event that the central locking or remote fob/smart key fails to operate the central locking and ignition.

If the flat key doesn’t start the car then it may be the ignition switch that’s at fault.
Are you certain that the flat key you have does belong to your car?

Dec

 

[Cw-kid]

Today I have not tried the "flat" spare key, as the car broke down at my parents house and the spare "flat" key was at my home. I will take the spare key down there tomorrow and try that to see if it starts the car?

I am not 100% certain that the flat key belongs to the car, but it was the spare key I was given with the car 12 years ago when I bought it second hand!

 

[Dec]

If your regular smart key is at fault, and the ignition switch is ok, then the flat key should start the car, the flat key most likely is the original key and dose belong with the car… just saying in case there is any doubt about it.

Dec

 

[Cw-kid]

Dec thanks for your help!

So I'll try the flat key tomorrow and report back.

If the flat key works, it looks like I will need a new smart key. Any idea on cost from MB?

If the flat key does not work, then it might be the EIS ignition switch?

If I bought and fitted a second hand EIS part would Merc then recode my smart key to work with that EIS? Or would it be better to buy a new EIS.

Due to the age of the car I am reluctant to start buying new expensive parts for it unless I really have to etc.

Cheers

 

[Dec]

The do sell these sets on eBay… for example… MERCEDES W202 C250 TD ECU SET WITH STEERING LOCK AND KEY 0225459632 | eBay

Also… MERCEDES W202 C CLASS C200 ENGINE ECU AND KEY SET 0285454232 MANUAL | eBay

I have no idea how it all works, others may know more but its unlikely that an MB dealer will recode any second hand parts, if the need recoding, the will only sell new stuff and will probably want to fit it themselves.

A replacement key is around £225, if the flat key works then at least you can lock and drive for now.

Dec

 

[Cw-kid]

Good morning

The spare flat key works and instantly starts up the car first time!

So looks like the EIS is OK and its the smart key fob.

So what are my options if any for a cheaper key replacement?

Cheers

 

[Cw-kid]

Rang Mercedes they want £230 inc VAT for a new key fob and metal key slide it comes pre-programmed for my car apparently. They also need a copy of my V5 document and photo ID!

 

[John Jones Jr]

Good morning

The spare flat key works and instantly starts up the car first time!

So looks like the EIS is OK and its the smart key fob.

So what are my options if any for a cheaper key replacement?

Cheers

Happy to hear that.

Did you price a new EIS unit?

 

[Dec]

Do nothing and just do without the convenience of remote locking and just use the metal key to lock up.
Spend £230 on a new remote fob.
Try and fix the faulty key, maybe the buttons on the faulty key are working and it is the vacuum pump that’s not working.
To check to see if the vacuum pump is working, close all the doors and see if the central locking switch on the dash will lock and unlock the doors, I think ignition might need to be ON for the central locking switch to work.
Check all fuses that are in any way related to locking.

Dec

 

[Cw-kid]

I've got a bigger problem now I've done something really stupid. I disconnected the battery and closed the boot went in to the house for 10 mins and now the boot has locked and I cannot open it. Neither of the two blade keys I have seem to fit in to the boot lock at all.

I've removed the first aid kit box to see if I could reach for the handle for the folding rear seats but the holes in the metal parcel shelf at too small.

So now I am really buggered.