Hello all, first off, apologies if there is a tread already on this. I am new to this forum and have searched for hours but have no found anything (got grey hairs to prove).

Ok, so...I got a 1.8tdci focus 55 plate with nearly 100k on the clock, that I am fixing up and selling for a friend. He mentioned (before I took the job) that the fuel pressure regulator/valve (Situated in front of the block)(sensor connected to the spider manifold) needed replacing. I replaced the fuel regulator valve and had the car connected to the diagnostics. Assuming that it just needed the sensor clearing of faults. Instead the car came back with three different fault codes: p0001,p0089 and p0670 (glow plug fault). I changed the fuel filter (which was filthy), ran the car but limp mode is still present. So my questions are:

1. Can fault code p0670 cause the car to go into limp mode?
2. Is fault code p0089 referring to the inlet metering valve (situated on the fuel pump)?

Has anybody had any experience with fuel pressure problems and how did they solve it? Also will the fault clear if I solve the issue or will I need to clear the faults manually? Any Info or suggestions will be greatly appreciated