I accidently put diesel in my unleaded petrol fabia.

Ever since a mobile mechanic drained the fuel system the fabias fuel gauge needle is stuck at the original level  and it isn't dropping while driving.

And neither is the onboard computer 'Range'.

Can anyone help?

 

Edited 5 October, 20241 yr by Gazbc
missed wording

How many petrol refills or partial refills have you done since the drain, have you driven the car much since - it could be something like the fuel tank sender and/or float needs a good shake up to unstick it or it needs replacing (I've no idea how easy or or not it is to replace),  Personally, where safe and reasonable to do so, I'd drive the car about with some gusto on bends and and heavy to stop braking with the fuel level at just above or anywhere below what it was when the diesel was drained out.

 

Otherwise perhaps (but I don't know) there's a computer reset required using an appropriate level scan tool suitable for your model and year of VW product (make sure the scan tool program is fully up to date for your model and year.

 

Others than me will know more with certainty, I always like to try simple, quick, easy, free methods that don't involve me getting my hands dirty or farting about with cars before moving on.  If a scan tool isn't available I also have a simple method to try for that but its unpopular here with some and it's suggestion seem to really upset them.

 

Good luck let us know how you get on.

 

Where did he drain the fuel from? Engine bay, underneath, or via the cars interior?

 

I'd imagine if the senders not been taken out and damaged, it will sort itself out after a couple of full tanks of fuel. 

Edited 6 October, 20241 yr by StevesTruck

Thanks for the replies, the fuel was drained from the fuel tank, i put in a partial 22 litres after the drain job was done, i covered 12 miles to get home, when i got home my OBD2 Autel AutoLink AL619 diagnostic scan tool said no trouble codes.

I dont think it can reset car computer.

Just one partial 22 litre refill since the drain job yesterday 5th oct 2024.

 

A quick look shows the AL619 does live data but I've no idea what it shows, also says it's updateable via online.  There are ways to test the sender but I'd still go with partial refills to just above the drain levels and driving around below and well below or above that level with a bit of sharpness to braking (how much that helps might not be much).  When my neighbour's rarely driven car fuel gauge (reading) got stuck I tried adding a gallon or so of fuel and quick runs round and round a few empty roundabouts in both directions and some sharp braking but no difference then next time I went to drive the car the gauge (reading) seemed to just unstick itself and was fine from them on. Just the type of non-PITA, non-farting-about-on-cars, clean-hands "repairs" I much prefer.

 

https://www.autelstore.co.uk/upload/pro/19082915670644993029.pdf

 

Thank you nta16, yes it seems the overall advice from everyone so far is to drive around and do partial refills and see how it goes.

Thank you all so far,I will keep you all updated.

To be fair, I'd probably tank it and run it low a couple of times so it sees the difference in level. The gauge isn't hooked directly to the level sender, so the electrickery probably wasn't expecting to see all the fuel disappear and a new level appear. 

7 minutes ago, StevesTruck said:

To be fair, I'd probably tank it and run it low a couple of times so it sees the difference in level. The gauge isn't hooked directly to the level sender, so the electrickery probably wasn't expecting to see all the fuel disappear and a new level appear. 

Yes i will try that, i have been out driving today for about 20 miles, the needle hasnt moved and the computer 'range' is still at 320 miles, the same as yesterday.

Ok, i will fill up tomorrow and see how it goes, i will keep you all updated.

Poor little thing's confused, so yeah, I'd say it needs a big change of fuel level once of twice to sort itself out. All assuming the mechanic hasn't done something daft to the level sender. 

Edited 6 October, 20241 yr by StevesTruck

9 minutes ago, StevesTruck said:

Poor little thing's confused, so yeah, I'd say it needs a big change of fuel level once of twice to sort itself out. All assuming the mechanic hasn't done something daft to the level sender. 

Ok thanks pal, fingers crossed it will sort itself out, the advice on here seems to point to that.

time will tell.

The float on the sender unit is on a very thin arm and could very easily have been compromised if that was where the fuel was accessed from

 

 

Make a note of your mileage and fuel filling and see if it ever starts to drop the needle.

 

Edited 6 October, 20241 yr by Stonekeeper

12 minutes ago, Stonekeeper said:

The float on the sender unit is on a very thin arm and could very easily have been compromised if that was where the fuel was accessed from

 

 

Make a note of your mileage and fuel filling and see if it ever starts to drop the needle.

 

Ok, will do.

Being used to very old cars and driving back in the very old, and nearer, days I'm used to the habit of driving using the tripmeter as a fuel gauge, means always filling the tank on refills if the gauge is inaccurate anywhere near the full mark or not working at all.

 

If the sender and guage aren't directly linked and go through one of the overlord computer program then personally I'd turn the computer "off 'n' on agen" by depriving and depleting it/them of power (in two both senses) as I prefer the computers working for me and not the other way round.  There must be some kind of switch around the fuel filler to let the overlords know when the car is being refuel so perhaps checking that area is clean and unrestricted (there's also often a drain for water to keep clear.  I can't remember if I've clean that on my wife's Fabia or not, certainly did on her hire SEAT Arona that was full of debris in the filler area behind the flap.

 

The needle gauge and range computer are now working ok, thanks everyone for your advice.