Petrol In My Audi A3 Diesel Then Drove 205 Miles??


Registered User
The fools mistake!!!

I put 30 quid worth of unleaded into my diesel Audi A3 and drove 205 miles. I filled this up and 2 days later when i went to drive home it wouldn't start. After the AA looking at it and them not knowing what was wrong?? they got it started for me and i was on my way home. I got there and decided to ask my neighbor to have a look as he is a mechanic, he old me straight away i had put petrol in instead of diesel. He told me to go and fill it up at the local garage with diesel supreme the good stuff and also but an injector cleaner to put in there aswell which i did. I have been driving my car for the last week and its not great but as the days go on its starting normal and not so sluggish now. As you can imagine i am worried about the future implications of this! and that in time this could cost me a lot of money!!! I'm wondering what sort of damage has been done and if there is anything i can do to stop my car dying on me anytime soon?


Registered User
Sounds like you may need to rebuild your fuel pump (tandem/lift pump)

Petrol doesn't have the lubrication that diesel has and it dries out the pump & rots the seals on pump & possibly injectors

I would get the pump checked at least, change the fuel filter, check/replace oil & filter (it could be leaking fuel inside the pump/injectors in to the engine block, first sign is oil smells of fuel, is thinned out & level exceeds high limit)

£30 of petrol & 205 miles before noticing is quite a while to be honest I'm surprised it lasted that long, but depends on how much diesel you had in there too

What year or engine do you have?

Don't fret too much if it's getting better though, best get it checked but you may have not done too much damage/if any. Diesels will run on pretty much anything liquid & flammable!


Registered User
In my old 1997 mondeo TD - in the winter I used to put a few litres of pertrol in with the diesel - made it run a lot better in the winter.
This was not a common rail diesel to was less fussy.


Registered User
id like to congratulate on how you managed to do 205miles on £30 worth of petrol lol especially after it should of been diesel. probaly lasts 100miles for me.

obviously diesels get more miles per tank but how still all those miles when having petrol in instead of diesel. would the petrol not burn at the same rate as being in a petrol car? or is the explosion alot less


Registered User
Diesel contains more potential energy than petrol. Mpg from petrol is literally the bottom of the list of priorities when misfuelling


Registered User
Diesel contains more potential energy than petrol. Mpg from petrol is literally the bottom of the list of priorities when misfuelling
Haha quality!

Fingers crossed for ya OP, but as others have said if it's improving you can't have done any huge damage, may have seal damage though but lesser of evils!


Well-Known Member
VCDS Map User
Don't stress...the fact that it is getting better is good news!

Keep using good quality fuel (without wanting to start a discussion on fuel I'd say use Shell or BP diesel, it doesn't need to be V-power or BP Ultimate), get the fuel filter changed and use the injector cleaner.

Take it for a nice long, fast drive on the motorway and it should be absolutely fine.

Congratulations on doing 205 miles before the car giving up, I was surprised it went so far lol.