1.5 tsi reliability

cupra14

Active Member
Aug 31, 2017
342
65
England
Is it actually getting the wrong MPG (by a significant amount)?

If it definitely is, check whether all the supported OBD monitors are set, whether it's running Closed Loop and what the fuel trims are.
 

SRGTD

Active Member
May 26, 2014
2,441
1,322
How are you measuring your MPG?
The trip computer has several variations -
MPG for trip
MPG since fill up
Long term MPG
Instantaneous MPG
That’s what I’ve been wondering.

@Tester01 - if you’re relying on your car’s fuel computer for your mpg figures, maybe it’s faulty and has been giving incorrect readings. Calculating your mpg manually or using an app such as Fuelly should give a more accurate view of your true fuel consumption.
 

Tester01

Active Member
Oct 24, 2022
91
11
That’s what I’ve been wondering.

@Tester01 - if you’re relying on your car’s fuel computer for your mpg figures, maybe it’s faulty and has been giving incorrect readings. Calculating your mpg manually or using an app such as Fuelly should give a more accurate view of your true fuel consumption.
I’ll try manually And see if it matches up.
Hopefully I have my receipt somewhere from last fill up.

or next time I fill up I’ll be sure to make note the litres etc
 

Tester01

Active Member
Oct 24, 2022
91
11
Is it actually getting the wrong MPG (by a significant amount)?

If it definitely is, check whether all the supported OBD monitors are set, whether it's running Closed Loop and what the fuel trims are.
What would be a good fuel trim reading?

last time I checked I do recall seeing closed loop when I looked on live data on OBDeleven weeks back.

But wasn’t sure what is relevant and what would be deemed abnormal.
 

Tester01

Active Member
Oct 24, 2022
91
11
Is this normal for Oxygen Sensor bank 1 sensor 2?
Been reading up on normal readings and not sure if I’m interpreting correctly.

Did a live data reading when I got home this evening.

The
Oxygen sensor bank 1 sensor 2 (jump sensor)
Voltage - 0.670 V

Fluctuated around 0.6 - 0.7ish

this was at idle.

If ive understood it shouldn’t be this high?

Still trying to diagnose poor Fuel economy issue but going in for major service this weekend. So see if that makes a difference but curious about oxygen sensor performance
 

SuperV8

Active Member
May 30, 2019
1,361
608
Is this normal for Oxygen Sensor bank 1 sensor 2?
Been reading up on normal readings and not sure if I’m interpreting correctly.

Did a live data reading when I got home this evening.

The
Oxygen sensor bank 1 sensor 2 (jump sensor)
Voltage - 0.670 V

Fluctuated around 0.6 - 0.7ish

this was at idle.

If ive understood it shouldn’t be this high?

Still trying to diagnose poor Fuel economy issue but going in for major service this weekend. So see if that makes a difference but curious about oxygen sensor performance
Your ECU 'knows' what values to expect from all the various sensors. If the O2 sensor was giving readings outside of an acceptable limit it would give you a fault code.
 

mty12345

Active Member
Jun 17, 2011
3,777
479
bristol
Is this normal for Oxygen Sensor bank 1 sensor 2?
Been reading up on normal readings and not sure if I’m interpreting correctly.

Did a live data reading when I got home this evening.

The
Oxygen sensor bank 1 sensor 2 (jump sensor)
Voltage - 0.670 V

Fluctuated around 0.6 - 0.7ish

this was at idle.

If ive understood it shouldn’t be this high?

Still trying to diagnose poor Fuel economy issue but going in for major service this weekend. So see if that makes a difference but curious about oxygen sensor performance
ECU only uses the 1st lambda sensor for fueling, sensor 2 is only to monitor if your cat is working properly
 

Tester01

Active Member
Oct 24, 2022
91
11
Your ECU 'knows' what values to expect from all the various sensors. If the O2 sensor was giving readings outside of an acceptable limit it would give you a fault code.
Ah just that I’ve heard that sensors can become lazy and sometimes don’t throw a fault code.

well then I have no idea why my mpg is so terrible. Now had all the filters and plugs changed
 

'& Son' managed

Third Party
Mar 2, 2018
270
89
South Coast
Not trying to add to the chaos but one possible factor that's not come up is that the
fuel economy readings can be set to display MPG in either 'normal' Imperial gallons,
or the smaller US units - which of course would lead to lower figures being displayed.

If everyone already knew this then I'll just get my coat...
 

Tester01

Active Member
Oct 24, 2022
91
11
Not trying to add to the chaos but one possible factor that's not come up is that the
fuel economy readings can be set to display MPG in either 'normal' Imperial gallons,
or the smaller US units - which of course would lead to lower figures being displayed.

If everyone already knew this then I'll just get my coat...
How do you check, what it’s set to?
Although I’m 100% sure it’s set to normal values and not displaying US units.

Even so completely ignoring the MPG readings, me getting around 300ish miles from a fuel tank is awful lol
 

'& Son' managed

Third Party
Mar 2, 2018
270
89
South Coast
How do you check, what it’s set to?
Although I’m 100% sure it’s set to normal values and not displaying US units.

Even so completely ignoring the MPG readings, me getting around 300ish miles from a fuel tank is awful lol
Can be checked in 'settings' on the central screen - it offers the options of 'Euro' litres per Km along with
'Imperial' MPG and 'US' MPG. I agree it's highly unlikely that anyone would have set it to 'US' gallons, but
it is possible.

More to the point, any 1.5 TSI should of course be attaining a range of at least 400 miles from a full tank.
My '150 EVO' Golf Estate has no problem managing that and always returned averages in the mid-40's,
with 50+ MPG being quite common travelling 4-up on longer journeys.

Since it's 'Stage 1' remap last year the average MPG figures improved further by about 4% - if you don't
play around with the extra power too often:redface:
 

Tester01

Active Member
Oct 24, 2022
91
11
Can be checked in 'settings' on the central screen - it offers the options of 'Euro' litres per Km along with
'Imperial' MPG and 'US' MPG. I agree it's highly unlikely that anyone would have set it to 'US' gallons, but
it is possible.

More to the point, any 1.5 TSI should of course be attaining a range of at least 400 miles from a full tank.
My '150 EVO' Golf Estate has no problem managing that and always returned averages in the mid-40's,
with 50+ MPG being quite common travelling 4-up on longer journeys.

Since it's 'Stage 1' remap last year the average MPG figures improved further by about 4% - if you don't
play around with the extra power too often:redface:
Will take a look tomorrow!

I’m actually stumped as what it could be and what I could try next.

Main dealer once again told me it’s normal when I went in for some advice.

I questioned if it’s maybe a clogged fuel filter but they said my car doesn’t have a fuel filter?
I believe typically they’re change during services for diesels then for petrol engines?

So just a bit lost.

I understand cold weather and short journeys kill fuel economy.

however no way my car should be struggling to reach 40MPG on a way 40 mile motorway trip for example

Especially if your estate that’s heavier on the same 1.5 Engine can easily get that, with passengers on board. Yet I keep getting told it’s normal.

maybe it’s time to cut my losses and get rid because it’s just odd.

Whilst I don’t think it’s mapped by the previous owner is there anyway of checking? I probably should have asked when it got serviced by main dealer as presume they have the tools to do so. From previous logs via OBDeleven I know the software number is 05E906018AL - which I believe is the stock ecu software version. But dunno if there’s anything else I can check to ensure it’s not got a dodgy map on the engine that could be causing issues

edit: for my own sanity checked units and they’re set to MPG uk
 
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SuperV8

Active Member
May 30, 2019
1,361
608
Will take a look tomorrow!

I’m actually stumped as what it could be and what I could try next.

Main dealer once again told me it’s normal when I went in for some advice.

I questioned if it’s maybe a clogged fuel filter but they said my car doesn’t have a fuel filter?
I believe typically they’re change during services for diesels then for petrol engines?

So just a bit lost.

I understand cold weather and short journeys kill fuel economy.

however no way my car should be struggling to reach 40MPG on a way 40 mile motorway trip for example

Especially if your estate that’s heavier on the same 1.5 Engine can easily get that, with passengers on board. Yet I keep getting told it’s normal.

maybe it’s time to cut my losses and get rid because it’s just odd.

Whilst I don’t think it’s mapped by the previous owner is there anyway of checking? I probably should have asked when it got serviced by main dealer as presume they have the tools to do so. From previous logs via OBDeleven I know the software number is 05E906018AL - which I believe is the stock ecu software version. But dunno if there’s anything else I can check to ensure it’s not got a dodgy map on the engine that could be causing issues

edit: for my own sanity checked units and they’re set to MPG uk
How many miles do you do to a full tank of fuel?
 

SuperV8

Active Member
May 30, 2019
1,361
608
Filling to the brim I probably get around 300 - 320 if I’m lucky, before having to fill up
I think you have a GPF in your 1.5tsi?
I have read that when these are trying to regenerate your MPG goes very poor - maybe yours is 'struggling' to regen?
 

Tester01

Active Member
Oct 24, 2022
91
11
I think you have a GPF in your 1.5tsi?
I have read that when these are trying to regenerate your MPG goes very poor - maybe yours is 'struggling' to regen?
Don’t know it’s hard to tell seeing as there’s no dash warnings etc.

I did try what @SRGTD suggested in one of his other threads to force a regen yesterday.
By on the motorway getting up to 70mph in gear 5 then letting it drop down to 60MPH by easing off accelerating. Several times.

But don’t think it did anything tbh.

Unsure if there’s any sure way of checking if it does have a GPF for sure.
As manual seems to suggest it’s only 2.0 TSIs that do.

And the fact my MPG has been pretty crappy for months

Weird and frustrating

Regret not getting the 1.4 I was initially interested, I let the digital dash and lower mileage lead me to the 1.5 lol.
Big mistake.
 
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SuperV8

Active Member
May 30, 2019
1,361
608
Don’t know it’s hard to tell seeing as there’s no dash warnings etc.

I did try what @SRGTD suggested in one of his other threads to force a regen yesterday.
By on the motorway getting up to 70mph in gear 5 then letting it drop down to 60MPH by easing off accelerating. Several times.

But don’t think it did anything tbh.

Unsure if there’s any sure way of checking if it does have a GPF for sure.
As manual seems to suggest it’s only 2.0 TSIs that do.

And the fact my MPG has been pretty crappy for months

Weird and frustrating

Regret not getting the 1.4 I was initially interested, I let the digital dash and lower mileage lead me to the 1.5 lol.
Big mistake.
Seems related to WLTP - if yours is WLTP is will have a GPF - if pre WLTP is without.
 

SuperV8

Active Member
May 30, 2019
1,361
608
What’s WTLP and how do I tell?
WLTP is the later emissions standards -

For the 1.5tsi seems like PR codes determine with or without filter - GPF
I think;
DADA engine code is without GPF
DPCA engine code is with GPF

1679053515352.png
 

Tester01

Active Member
Oct 24, 2022
91
11
WLTP is the later emissions standards -

For the 1.5tsi seems like PR codes determine with or without filter - GPF
I think;
DADA engine code is without GPF
DPCA engine code is with GPF

View attachment 36060
Well guess that solves it if that’s correct then mine doesn’t have GPF as it’s DADA.

Guess that’s ruled out.

Alrhough it’s annoying there’s no clear way of checking if it does or doesn’t. And lot is guess work or trying to piece info together.
Needs to be more transparency
 
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