FSI suddenly using massive amount of fuel

SoftwareAndSwarfega

SoftwareAndSwarfega

Member
Hi

This evening I set off on a 17 mile trip to my father’s house in my 1.6 FSI. I had close to a full tank, only 40 miles since last filled. When I started the (cold) engine I got a temperature warning on the driver display - something if not seen before - which disappeared after a minute or two. The temperature showed 60 for a few minutes and then crept up to normal and stayed there.

I proceeded to drive to my dad. It was rainy and dark so I was obviously mostly keeping my eyes on the read, so I didn’t notice the fuel gauge on the way or when I arrived, however when I left to go home I saw that I only had 1/2 tank indicated on the gauge (yes, half). And the temperature warning popped up again, then again vanished. I started to drive, hoping the fuel needle would move up - but it didn’t. It continued to fall - not quite fast enough to see the needle move, but enough to be discernible each minute. Then, about 3 miles into the journey home and on the motorway, my engine light came on. I had no choice but to keep going, but I took it easy. By the time I arrived home (18 miles) I’d nearly used another 1/4 tank and was nearing the red.

The engine was not unusually loud, revs and pick-up were ok, but something felt off, sluggishly heavy slightly. There was no smell of fuel, no obvious leaks, no slick on the road where I parked.

I haven’t had a chance to check with VCDS but may get a chance tomorrow.

I know living with an FSI is never easy, but this combination of events has kind of blown me out of the water. So, if my description rings a bell with anyone or you know what the symptoms might mean, then please let me know.

Thanks 🙏🏻
 
Too many simultaneous issues there. Whilst I can not rule out the fuel sender or gauge has gone faulty a full VCDS scan may help but not everything is monitored. You would be wise to carefully check the cars main electrics as that can easily be the source of multiple issues., By that I mean the battery is good and holding charge, the alternator is pushing 14 plus volts into the battery when running, the battery terminals are clean and tight and the auxiliary positive connections are tight and tight on the positive terminal, and the main engine earth is intact, tight and actually working.

Dampness in the alternator could have caused a short causing circuits to loose power enough to generate faults.
 
Reading the start of your post it seemed simple, low coolant, drive a few metres, coolant sloshes around to satisfy level sensor and the temperature warning is cancelled. Obviously check coolant level.

What comes next blows this simple explanation out of the water, yes perform a VCDS scan.

Andy
 
SoftwareAndSwarfega said:
Hi

This evening I set off on a 17 mile trip to my father’s house in my 1.6 FSI. I had close to a full tank, only 40 miles since last filled. When I started the (cold) engine I got a temperature warning on the driver display - something if not seen before - which disappeared after a minute or two. The temperature showed 60 for a few minutes and then crept up to normal and stayed there.

I proceeded to drive to my dad. It was rainy and dark so I was obviously mostly keeping my eyes on the read, so I didn’t notice the fuel gauge on the way or when I arrived, however when I left to go home I saw that I only had 1/2 tank indicated on the gauge (yes, half). And the temperature warning popped up again, then again vanished. I started to drive, hoping the fuel needle would move up - but it didn’t. It continued to fall - not quite fast enough to see the needle move, but enough to be discernible each minute. Then, about 3 miles into the journey home and on the motorway, my engine light came on. I had no choice but to keep going, but I took it easy. By the time I arrived home (18 miles) I’d nearly used another 1/4 tank and was nearing the red.

The engine was not unusually loud, revs and pick-up were ok, but something felt off, sluggishly heavy slightly. There was no smell of fuel, no obvious leaks, no slick on the road where I parked.

I haven’t had a chance to check with VCDS but may get a chance tomorrow.

I know living with an FSI is never easy, but this combination of events has kind of blown me out of the water. So, if my description rings a bell with anyone or you know what the symptoms might mean, then please let me know.

Thanks 🙏🏻
Click to expand...
If there's a petrol station close by, I'd suggest filling it, to see how much fuel is in there. That would either confirm the gauge as incorrect, indicating an electrical fault, or the gauge is correct, indicating a mechanical fault.
Mac.
 
SoftwareAndSwarfega said:
Hi

This evening I set off on a 17 mile trip to my father’s house in my 1.6 FSI. I had close to a full tank, only 40 miles since last filled. When I started the (cold) engine I got a temperature warning on the driver display - something if not seen before - which disappeared after a minute or two. The temperature showed 60 for a few minutes and then crept up to normal and stayed there.

I proceeded to drive to my dad. It was rainy and dark so I was obviously mostly keeping my eyes on the read, so I didn’t notice the fuel gauge on the way or when I arrived, however when I left to go home I saw that I only had 1/2 tank indicated on the gauge (yes, half). And the temperature warning popped up again, then again vanished. I started to drive, hoping the fuel needle would move up - but it didn’t. It continued to fall - not quite fast enough to see the needle move, but enough to be discernible each minute. Then, about 3 miles into the journey home and on the motorway, my engine light came on. I had no choice but to keep going, but I took it easy. By the time I arrived home (18 miles) I’d nearly used another 1/4 tank and was nearing the red.

The engine was not unusually loud, revs and pick-up were ok, but something felt off, sluggishly heavy slightly. There was no smell of fuel, no obvious leaks, no slick on the road where I parked.

I haven’t had a chance to check with VCDS but may get a chance tomorrow.

I know living with an FSI is never easy, but this combination of events has kind of blown me out of the water. So, if my description rings a bell with anyone or you know what the symptoms might mean, then please let me know.

Thanks 🙏🏻
Click to expand...
Got a very similar problem with my FSI, albeit less drastic. Got 235 miles out of my last full tank. I get an ABS light and a (( ! )) warning every now and then, no engine light.
 
safbeafbe said:
Got a very similar problem with my FSI, albeit less drastic. Got 235 miles out of my last full tank. I get an ABS light and a (( ! )) warning every now and then, no engine light.
Click to expand...
I'd suggest you're driving a vehicle in an unsafe condition. Brakes that work are quite important, don't you agree?
It's in your interest to get it scanned and fixed.
No obvious correlation between brake system and fuel consumption, but scan might help there too.
Mac.
 
PlasticMac said:
I'd suggest you're driving a vehicle in an unsafe condition. Brakes that work are quite important, don't you agree?
It's in your interest to get it scanned and fixed.
No obvious correlation between brake system and fuel consumption, but scan might help there too.
Mac.
Click to expand...
Aye. The car's condition is a bit of a mystery at the moment, trying to get it scanned ASAP, as it behaves normally despite the warnings. But of course this doesn't mean it's safe - I have little choice but to use it for my commute. Cheers Mac
 
PlasticMac said:
If there's a petrol station close by, I'd suggest filling it, to see how much fuel is in there. That would either confirm the gauge as incorrect, indicating an electrical fault, or the gauge is correct, indicating a mechanical fault.
Mac.
Click to expand...
Thank you for the suggestion. I had every intention of doing exactly this after performing a VCDS scan, so last night I performed the scan; nothing major, just a lambda sensor. However, when I switched on the ignition in order to do the scan the fuel gauge moved up and indicated over 3/4 tank… so it does seem that my issue was primarily an electrical gremlin.

I’ll obviously also check the coolant.

Many thanks again.
 
SoftwareAndSwarfega said:
Thank you for the suggestion. I had every intention of doing exactly this after performing a VCDS scan, so last night I performed the scan; nothing major, just a lambda sensor. However, when I switched on the ignition in order to do the scan the fuel gauge moved up and indicated over 3/4 tank… so it does seem that my issue was primarily an electrical gremlin.

I’ll obviously also check the coolant.

Many thanks again.
Click to expand...
🤞Mac.
 
safbeafbe said:
Got a very similar problem with my FSI, albeit less drastic. Got 235 miles out of my last full tank. I get an ABS light and a (( ! )) warning every now and then, no engine light.
Click to expand...

Check your brake fluid level


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