As per title, any help with this is really appreciated.

I have a 2006 Focus 1.8TDCi which I've owned since new and it's now just reached 70K Miles.

A few months back the following problem occured:

When driving the car, the "engine systems fault" warning comes on, accompanied by the little red warning lamp. It normally happens when putting the engine under load in 5th gear - i.e trying to overtake but I can also cause the error show up by flooring the accelerator pedal in the lower gears too (not something I'm in the habit of doing - just did it to get the error to show up).

When the warning has come on, there is a noticeable loss of power - if I press the throttle pedal down to accelerate, it just refuses to rev and I have to back off the pedal then re-apply only slight foot pressure to gradually build the speed back up. This works until I have to drive up any incline - I ended up having to slow to 30mph and get on the hard shoulder on the M2 the other night on that long climb from the River Medway - not good!

I've had three different OBDII-readers plugged into the car with the error message up on the dash but there's NO error codes coming up on the fault-code reader .

We're not that well off at the moment so I don't really want to pay Ford loads of money just to plug another machine into it, has anyone on here had the same problem with their Focus 1.8 TDCi? If so, what was the defective part?

I've heard that the throttle pedal potentiometer and throttle body can cause problems. I just really hope it's not the turbo or fuel pump! ££££

Thanks for your time, Jim.

Not had the same problem, but as an aside, when was the last fuel filter change?? It may be this thats dirty, if fuel cant get through to the injectors. Sounds like once the warning light has come on, its gone into Limp Home mode, and I wonder if fuel starvation has done it. you saying you either load the engine or floor it, so it needs more fuel made me think of this.

Just a thought, and may be completely wrong...

[quote name='ChrisH' timestamp='1328477745' post='165001']
Not had the same problem, but as an aside, when was the last fuel filter change?? It may be this thats dirty, if fuel cant get through to the injectors. Sounds like once the warning light has come on, its gone into Limp Home mode, and I wonder if fuel starvation has done it. you saying you either load the engine or floor it, so it needs more fuel made me think of this.

Just a thought, and may be completely wrong...
[/quote]

Thankyou Chris, much appreciated. I have a new fuel filter and will be fitting it this weekend - hopefully it'll cure it!.

Cheers.

No probs, i hope it cures it.. if its not that, could be the air mass sensor, but that should log a code anyway.

The car is now back to full health and driving perfectly

Chris, you were spot-on, it was the fuel filter! When I removed the old filter, it was in a very sorry state - completely black and clogged to death. Fitted the new filter and took it for a 20-mile test drive, giving it loads of throttle in all gears on a nice, long stretch of road and no warning lights. It also felt a bit more sprightly.

I guess that there's a fuel-volume sensor that throws its toys out of the pram, putting the car in limp-mode before any engine damage an occur from fuel starvation?

I have had the car serviced at the correct intervals, I guess the garage decided to omit that particular item!

Thanks for your help Chris and hopefully anyone else with the same symptoms might find this thread.

Nice one Chris. Its especially nice to hear an inexpensive fix doing the job.

Fuel filters are replaced every 3rd service at a main dealer....

so that would be 37500 miles.........