Skoda fabia 2003. My fuel gauge has started behaving erratically. Sometimes it says the tank is empty when it is actually nearly full (and vice versa). Other times it appears accurate for while but then moves up/down while driving. On the occasions when the needle reads empty the fuel warning light doesn't come on (I'm guessing the needle and light run off different systems/sensors?)

 

I've done a bit of googling and I think I may need to test the sender unit with a multimeter to determine if this is where the fault lies. Can anyone tell me exactly where I should be placing the multimeter probes on the unit? And what resistance levels should I expect to see when the sender arm is in the full/empty position?

 

Is there any other basic things I should look at/check (wiring?) to help diagnose the problem?

 

Thanks, Rich

You may find that by far the quickest fix is simply to replace the entire sender unit which is under the rear seat squab.

Thanks for the reply. Yes, I've thought about just replacing it but my budget is tight so I was hoping to diagnose the problem before buying a new unit (incase the fault lies elsewhere - as I have seen in other people's cases).

 

It been like this for a month; I'm not in a great rush to get it working again as I'm currently not doing many miles and I just fill up the tank after 200 miles so I don't run out.

It's the pins that the thinner pair of wires go to at the fuel pump/gauge connector, pins 2 and 3, but if it's intermittent it may be hard to spot if the problem is thereabouts.  Not sure what resistances to expect, but just different when fuel level is high versus low. At some point in mk1 history, I seem to remember they changed the sender unit so it went the opposite way in terms of resistance change.

 

It could also be a cracked solder joint at the green connector on the instrument cluster circuit board. It comes in on pin 15, adjacent to the one in this picture labelled "coolant level".

check all the joints for cracks carefully while you're in there, if you do have a look.

 

Can't see what else the low fuel warning light/bong would sense off, so I'm a little confused about why that isn't registering.

 

 

Edited 9 December, 20196 yr by Wino

Thanks Wino - lots of useful info.  I had a look at the solder joints but couldn't see anything out of the ordinary.

 

It's due for MOT next month so may get the garage to have a look. But also tempted to make do and keep an eye on the trip clock until the rest of the car dies!

Hi, I know this is an old topic I have a very similar problem to you.  Erratic gauge reading, often reading zero but the empty tank warning doesn't come on.  Did you ever manage to fix your problem?  And has anyone else got any suggestions?