Can some 1 please help me with this

I've checked your VIN with Citroen and its a 2L 110bhp diesel without a particulate filter, which is a very good start.

P135x is usually related to glow plugs and glow plug relay, but I've never known them to put the car into limp mode if they're old or malfunctioning.

You don't mention your car's age or mileage or whether the plugs have been changed. That would be the second place I'd start - the first being to visually inspect the plugs and relay and all their wiring, giving them a spray with electrical contact cleaner.

I'm not sure what diagnostic equipment you used but you really need have have it scanned by LEXIA equipment as that can read live engine data and tell you the readings of components as they're being used, rather than a generic fault code which could indicate a faulty part, or could mislead you because another part in the chain is faulty.

Google "Lexia Owners Map" and you'll find details of a fellow Cit owner with the kit who will help you out.

Edited by Gibbo_Wirral on 09/12/2014 at 13:29

Its probably the HP diesel pump regulator, they cause most problems on these. You can get a new one on ebay for about £100 or a secondhand one for a lot less, they are not to difficult to fit.