Ford Mondeo III (2000 - 2007) - TDCi - Fuel gauge / computer discrepancy

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Fri 14 Dec 2007 22:56
TDCi - Fuel gauge / computer discrepancy - BobC
Last Thursday, I refulled from below a quarter to a full tank but there was no change to the available miles shown on the computer readout despite the analogue fuel guage showing the tank to be full. Later in the week, the low fuel warning light came on when the computer considered the remaining range was 50 miles (the gauge was still showing the tank to be full!) and I wondered if the ECU would stop the engine when the computer thought the fuel was about to run out. When I started the car the next day, the low fuel light was still on and computer showing only about 25 miles - 10 miles later, I noticed that the light gone and the available range was 720 miles.

I assume the most likely cause of the faulty reading is a poor electrical connection or the level reader in the tank rather than the computer. The car is coming towards the end of the 3 year warranty period but obviously is not faulty just now. Is this likely to be a simple fix if I choose to ignore it and hope it was a one-off incident that may not recur?

Any comments would be appreciated.

Edited by Dynamic Dave on 15/12/2007 at 00:02

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Sat 15 Dec 2007 10:15
TDCi - Fuel gauge / computer discrepancy - cheddar
It is probaly a minor fault like a connection as you suggest though could be an ECU fault which is costly, I would take it in to the dealer describe the issue as you have done here and ask them to investigate under warranty, if it is ECU there may be a fault code logged that they can read.

Even if they find no fault now if it re-occurs in a few months you will have logged prior to the warranty expiry.

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Sun 16 Dec 2007 14:24
TDCi - Fuel gauge / computer discrepancy - BobC
Cheddar,

Thanks for your comments. I have an outstanding booking for the dealer to look at this on Tuesday but I doubt they will be very interested unless it faults again before I take it in. I will refuel before taking it in to see if the fault recurs.
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Sun 16 Dec 2007 14:42
TDCi - Fuel gauge / computer discrepancy - mfarrow
See if the fault has been stored in the dash:

Turn the ignition on whilst holding down the trip reset. Wait for the gauges to sweep then press the trip button to go through the sytstem until you see DTC followed by a number or none. If there's a number report it back.

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Mike Farrow
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Sun 16 Dec 2007 20:03
TDCi - Fuel gauge / computer discrepancy - cheddar
See if the fault has been stored in the dash:


I think an ECU fault will only show via a reader though that is worth a try.

I would ask the dealer to make sure they plug it in and see if any codes are stored.
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Sun 16 Dec 2007 21:57
TDCi - Fuel gauge / computer discrepancy - BobC
Mike,

How long does the trip reset have to be held for? - the gauges don't seem willing to sweep. I made the mistake of turning ignition on the first time without pressing the trip reset - is it necessary to wait until the figures in display disappear before retrying?
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