Diahatsu Sirion 1.3 2005 model automatic, OD light blinks

Blockage in the exhaust is quite likely a cause.

something not replaced correctly check all fluids for level and for cross contamination --pressure test coolant and oil systems --check all sensors and wiring --timing

possible failure of the flex bit of the exhaust
you will have to take it to an accredited exhaust specialist shop to get a quote on the repair

its not that difficult just remember to loosen the pulley bolts before removing the fan belt. The belt helps to keep the pulley from turning making it easier to loosen the pulley bolts

What is he limp mode. you have not got enough fluid are u checking it warm and in park car has to be running to check tranny only, DO NOT OVERFILL IT LESS IS BETTER THAN OVER.

There should be no reason to 'adjust' the timing belt: it is either fitted and working or not fitted..therefore having to replace one? If you do have to replace one, it is not a job for the faint hearted! You will also have to make sure you have a spare car for back-up.. e.g: if you plan to do this job and get driving in short time think again... You need as much room, both visual and physical around the plastic timing cover, you need to ensure the timing cogs are pre marked (with dots) showing what is called TDC (top dead centre) ENSURE THESE DOTS LINE UP PERFECTLY BEFORE REMOVAL AND AFTER RE-FITTING NEW BELT.. apart from that crucial bit.. it's simply a matter of cleanliness and patience.. remember to loosen the belt tensioner prior and re-tighten after fitting new belt.. DO NOT OVER TIGHTEN!

drive belt side is one

No reverse is the most common symptom of a failed transmission. You will need to remove the ****** and have it rebuilt/overhauled.

if the transmission has a dipstick similar to the engine dipstick you fill it through that tube using a small funnel or the like.....hope this helps.....cheers.