I want to change my battery,on my peugeot 307 2ltr diesel but can this be done without loosing the codes

check the battery posts and terminals are shiny clean and tight. Check fusible link near the battery is ok. Have a load test done on the battery as there may be a dead cell

you may need a reader unit to reset the cpu.

I have done this before a few times, you can remove the top of the pump in situ. It is very awkward to put the top of the pump back on though. but can be done:)

anytime you disconnect the battery ,you will loose radio memory, clock ,and similar functions .Other than erace engine computor fault codes the engine system will keep the info that itneeds to operate

There is no need to change it frequently. If there is a loss of engine power or if throttle cuts out then may be its the time to change fuel filter. It is recommended by peugeot to change fuel filter (but depends on fuel purity) after every 36000 miles.

You can clean it yourself
Dipp the whole filter body in carosine oil tank and leave it in there for about 20-30 minutes
Pour some petrol in filter with the help of plastic piped and apply a slight air pressure (use a piece of pipe to blow) in the reverse direction (marked with arrows) of fuel supply to clear residue and heavy oil composite that clogged in filter.
Repeating the cleaning process 2-3 times will clean the filter to reuse it without the need of a new one to buy.

if it says the diesel filter, then that is what it means,a fuel filter.normal service requirement on any vehicle and can be done for small dollars at any garage

no its not right,either change the fuel filter and air filter .if still no joy then get someone to check the injector pump timing because it sounds like someone has changed the timing belt and not done it right..the cam and pump are locked up with a 8mm bolt through the gearwheel into a indent hole behind and ???sounds like weekend mechanic job ,couldnt or didnt know how to sort ot or what they done ??so flogged it quick

could be a dodgey starter motor, is the car petrol or diesel, if its diesel id recemend changeing the heater plugs and diesel filter thats if they have,nt been done in the lastyear or more

usually you should do it for peugeot diesel at 122000 miles along with water pump and the tensioner roller that runs under the cambelt too. But to be on the safe side do it at 100000 and save the fortune.
It took me (DIY job) about 6-8 hours as i wanted to save 450 pounds.

fuel diesel problem