S40 has no dash lights and won't turn over key error
 

Hi lads
I'm new to the site
My S40 2007 2.0 diesel comes up key error turn the key and nothing happens other than key error I bypass the starter motor and it starts in limp mode but still no wipers indicators no dash lights won't charge.
IV changed the CEM and the steering lock and the ignition barrel checked the wiring to the ignition all fine. I'm just wondering if anyone has had the same fault or a fix .
Thanks in advance moz88

"changed the CEM" - explain please? That part cant be just "swapped" from another car, has to be cloned to properly work. If you are currently on "swapped" CEM that may explain the "nothing works" issue.
Key error is 99% times connected with ignition module being faulty (SCU =- starter control module) - it doesnt recognise the RFID chip and doesnt allow car to start. That part CAN be just swapped from another car.
Other possiblity is that car has lost the key code - I heard it may happen on diesel models when battery is long-flat , car kinda "forgets" the code and needs reprogramming.

The car still starts when I power prob the starter. I unplugged the ECU and the exact same faults. And some times the steering lock makes a noise so I think the CEM is ok what do you think

Not sure, Im confused by your explanations.
If steering column does "bzzt" it means steering lock is disengaged upon detecting a correct key. It should also mean that when on POS2, all dash lights should work, wipers etc - does that happen?
THEN if you go to POS3 - starter - does error comes up or whats happening?

The steering lock only makes the noise some times not all the time. The car has nothing regardless of the key positions other than key error but put a live to the starter motor and it starts in limp mode. i don't think it's the key or the CEM. Does the ECU tell the CEM what to do or tell it it's one to turn on?

Sounds like the ignition switch, just had same with my v50. Put key in and nothing happens, steering lock doesnt come off and key error message.

IV replaced the barrel and still the same

I'm thinking of putting an ECU kit on it. What would I need to replace? I'm thinking I just need a key ECU and CEM .

Sounds like scl is faulty get vida and look for scl codes

Try this remove steering colum panels gently tap scl with hammer see if it starts

I put a full kit on ECU CEM key barrel steering lock and alarm module. All came to life but won't start turn the ignition off and it says 'immobiliser try start again'. I'm stumped now so might just give up and break it shame it's a nice car.