Fuel Guage fault.
 

I don't know if this has been mentioned before,but I had noticed my gauge going down sooner than I expected,so I put 50 euros in,then took my friend to the pharmacy,as I was waiting,I noticed the gauge was showing lower than a quarter tank,at first I thought I'd been short changed at the pump,then thought it might be leaking,badly. Then I remembered that the on board diagnostics could tell me how much fuel I have in the tank,sure enough after pressing the trip knob after turning on the ignition,I found it and it read 49.5 litres,.relief! No leak and I'd not been robbed.
Anyway to fix the gauge,all I did was scroll further and did a software reset,,gauge as now worked correctly for 5 days,so job done.
Hope this is useful for someone else.
It must be said that having four 75diesels over 19 years,I've never known this to happen,first time for everything!
Happy new year everyone,
Ken.

Thanks for that, you do it on the internal diagnostics?? if so which section did you use?

Hello Ken, it's amazing that few of us do the obvious thing when our electronic gizmos misbehave. This could be a good example of how a very common, often discussed issue with the fuel gauge might be explained. A software glitch. or mabe there's a bug. Most software has them so why not here? The 'Software Reset' option listed in the Diagnostic Mode has never been examined as far as I know. Certainly not in my time around here. There's likely a fear that it could have dire implications for the whole convoluted system, so nobody has risked pushing that particular button. So, for whatever reason, you did and seemingly fixed the fuel gauge. Congratulations, you may have discovered something new about Diagnostic Mode.

A useful next step would be for others with the wonky fuel gauge syndrome to bite the bullet and push the Reset button. Let's generate some data to support the hypothesis. A simple software bug would certainly be more plausible than the way-out theories I've read over the years.


I trust you've observed no other effects after the reset?


TC

This is very interesting - so you press the trip button up to number '19', then when 'log 1 off' is showing, you click through again to number '21'.

But how do you activate the reset once here ? Does it do it automatically, or is there another sequence of specific button pressing to get it to reset ??

Many thanks :xmas-smiley-008:

Yes I just pressed it again,once I reached 21,,everything else seems ok,,although my rain sensor isnt working,but that was before i did this,,,must be as brave when I connect TOAF, to sort that one out..
As I can't pop around to see Big Russ,unless he fancies a holiday in Gozo,Ha Ha,,

I still thought it prudent to check diagnostic re- fuel levels in the tank before narrowing it down to something wrong with the gauge.

Just a quick update regarding my fuel gauge issue I had last year.
Software reset did the trick with no other issues and guage has worked perfectly since.
This may help the chap who's having a problem at the moment.

Thanks for the update. It seems apparent from Ken's experience that problems with the fuel gauge may actually be of two kinds, hardware failure and software glitches. It's well known that physical wear in the central area of the float arm rheostats gives rise to readout errors. It seems to me unlikely that the Software Reset in the Trip Screen Diagnostic Routine will fix a worn out winding. So, not all fuel gauge issues are mechanical. This of itself is usefull additional info on how these things tick.


TC

Thank you! How do I find the guide to do the diognostic as I forgot where it is?