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Mike, UK Car Mechanic
Category: UK Car
Satisfied Customers: 39198
Experience:  Hi, I am a Car/ vehicle technician of 34 years. 29of -running my own repair/diagnostic business.
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What do I do about DTCs DF054 and DF055

Customer Question

What do I do about DTCs DF054 and DF055
Submitted: 2 years ago.
Category: UK Car
Expert:  Mike replied 2 years ago.

Hello and Welcome -

My name is ***** ***** Im happy to help / advise.

These codes you have are for faults on the cars immobilser system... This is why it plays up non starting Im afraid.

Really the way forward is to have the system further checked.... you need to have the key/s checked to see if its not transmitting properly - and the car - to see if its not receiving. It will be one or the other... and then its a case of replacing whichever part is found to be faulty.

Bear in mind though that these do suffer with rain ingress - check up under the dash - looking for wet getting onto /into the module.... this is common - often a good dry out.. disconnect -then re connect the module..and it will sometimes work / cure it.

if the module is damaged though and it wont work, it would need to be replaced.

There are some companies though that can provide a work round - a bypass for the system. SOME of these cannot be done that way but you would have to speak to the company and ask them to be sure... If this can be done, its often a cheaper fix -if it comes to replacement modules etc. One such company - in the UK HERE - click the link. contact them and speak to them - have the full details of your car with you when you contact them. ( The web page speaks about you list your keys - that's just one scenario - ignore that ..)

There is also a way to bypass the immobiliser using the CDL - locking switch inside - they can explain this too.

Let me know how you go..and / or let me know if you need anything further on this..

~~~>>>>>>~ Meanwhile now - Please do click on the "Exc / Ok rating" for me at this time.. Thank you in advance for that . ..

Note that you can get back to me anytime at all after doing the rating - it doesn't close you out -

- Best Rgds, MIKE.

Customer: replied 2 years ago.
Hi Mike
I did some research myself.I found some instructions in the Technical Note 3668A. You can easily Google it. To get further I need to locate the UCH. I can't find it. Please help. Also I can't remove the trim panel above the steering column. Please advise.The trim panel below the steering column is fixed with 3 screws. It came off easily.
Have a nice weekendBR
Customer: replied 2 years ago.
HI Mike
I also need to locate the ignition computer.
I think that the right time to rate your service is when I have got maximum information from you.BR
Expert:  Mike replied 2 years ago.

Hi again-

First my apologies for the delay as I wasn't on over this weekend... Usually I am, but I just couldnt be this time.

The UCH is under the dash on the Megane -

- They did swap the location depending on exact year / month of build - check up under the drivers side - its easily seen if its there - if not - its up behind the glovebox on the other side.

The Ecu is in the engine bay - again, these moved around but usually mounted on one of the suspension turrets...

If not there - its usually just behind the headlight in a metal surround / case.

I hope that helps you further.

Re the ratings , I would appreciate it if you would do that at this point - Thank you. I have answered your initial / main question. As I said, Im always happy to help further as / if needed after.

Thank you again,

Best Rgds , MIKE.