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Focus 2006 1.8 Tdci 'engine Systems Fault' Again!


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Hi all,

This is a long one, please bear with me. A few weeks ago my sons friend kicked the GEM in the passenger footwell and disturbed a connector causing numerous problems. This I found and after taking the time to clean all the connector blocks (should not have done that) the car was fine except for the 'Engine Systems Fault' coming up and going off on the screen. I had this before and after chaging the fuel filter it went. This time though with a better scanner I get the fault 'Pressure Control Valve Malfunction'. Still I changed the filter and it got worse. Ran the live data on my scanner for the PCV and Fuel rail pressure and noticed that the rail pressure was going to 15 - 20k psi when the system fault was showing and dropping to 4.5k psi when the message went out. At the same time the PCV was running between 0 to 20%. Checked all the connections and the rubber seal in the filter, all ok. No air in the system. Still get the fault on the screen. So I think I'll check the Pressure Control valve. It's getting a healthy voltage at 12.5v engine off and 14.5v running on one wire and between 3.7 & 4.5 volts on what I suppose is the control wire. I have no scope so I cant get a waveform.

Then I restart the car and the system fault stays on permanently, the PCV shows a flat 15% on the live data with no response to differing fuel rail pressures. It is also almost impossible to start now.

Everything I've done seems to make it a little worse. I may be a complete idiot and have buggered something up I dont know, I'm only a hobby mecahnic and really wish I had points and distributors back but, alas it's not to be. Is the fault electrical or is the PCV at fault????

Your thoughts would be appreciated.



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How about doing a resistance check on the control wire to ensure there is no breaks?

Sounds daft but its best to start with basics

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Sorry should have said I did that and got a couple of ohms but didn't think that was significant. I've ordered a new valve for now and seeing if it does the trick. I know its a gamble but if it isn't the fault at least I can go to Ford and say it is an electrical fault and leave it to their diagnostics. :)

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  • 2 weeks later...

Fixed! Seems I was barking up the wrong tree. It was the fuel pump that was faulty. A total coincidence that it came up after an electrical fault. Ever since I bought it I thought it was just a little down on power than the other 2 focus's we have in the house but put it down to being a Mk 2. New pump and it's the same as the Mk 1's. Very costly to repair and if the rest of the car hadn't been perfect I think I may of scrapped it but there you go. This may be of use to someone else with similar symptoms.

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