1995 Land Rover Discovery Tail Light Problem

The fuel filter will not cause the check engine light to come on,It will have to be scran, To find out why the light come on now.

Try checking earth points on light cluster

You need a noid light for that but since they are all not firing it's most likely the cam shaft position sensor. That tells the computer the cam shaft position so it knows when to pulse each injector. Let me know if that's it. The cam shaft sensor should be pretty cheap.

The red light means the Immobiliser has not been turned off, the deactivator in the key must not be working correctly, visit your local land rover dealer who will be able to make sure the key is paired to the car correctly, otherwise you may need a new key.

check so see if water runs out the tail pipe! if so head gasket

TAIL LIGHTS ARE NOT STOP LIGHTS.
THEY ARE THE LIGHTS THAT COME ON WHEN THE HEAD LIGHTS ARE TURNED ON.
THE MIDDLE LIGHT IS THE CENTER MOUNTED STOP LIGHT.
THIS HAS BEEN A LEGAL REQUIREMENT ON ALL SUV'S SINCE 1995.

The code P1451 on a Land Rover is "Leakage Detection Module Motor power stage error Drive cycle A:Signal out of range - above maximum". This is an OBD-II diagnostic system code. As far as I know, a 1995 Land Rover Discovery does not use a OBD-II system. Is it possible that this rover is a later model year

Check your charging system sounds as if the alternator has low output under load or when it is hot from runnig for a while.

have you checked the 20amp fuse it the fuse box under the bonnet on the drivers side

If your brake lights don't work Its because you blew the fuse  which Is located In the main fuse panel under steering wheel.  Without break lights your rover will fire up nice but wont shift out of park until you replace the fuse.  If your ABS Is acting up It Is also an easy fix.  Disconnect the ABS from each wheel.  You still got all wheel disc breaks that work great but no ABS.  Your other option is  thousands of $$.  If your breaks are weak check your master cylinder and make sure you got enough fluid and that you are not loosing the fluid.  If you notice you are leaking brake fluid because you have to keep filling it up but cannot find a leak anywhere.  I bet I know where It is.  Check your rear break lines and make sure one of them didn't get caught in your rear springs and pinched ever so slightly when you were doing dounuts In the snow.
Good luck,