We’ve had this ongoing problem with the engine warning light on (but not flashing) on my wife’s petrol 1.2 Fabia.  Had various fixes tried and  some ‘solve’ the problem for a short time.  However I have noticed the light goes out if you fill it with a full tank of petrol! However the light comes back on when the petrol level lowers to half and below. Could this be a useful clue to identifying the problem?  I make sure the petrol cap is secure every time. 

Edited 19 February, 20251 yr by Jazajon

Ideally you should get the car’s controllers ready with a VW Group fully compliant scan tool, and use the logged faults as a starting point while also considering what you have also discovered.

Hi, welcome.

 

6 hours ago, Jazajon said:

However I have noticed the light goes out if you fill it with a full tank of petrol! However the light comes back on when the petrol level lowers to half and below. Could this be a useful clue to identifying the problem?  I make sure the petrol cap is secure every time. 

Have you checked the petrol cap fully seals fully?  Make sure there's no grit or muck on cap or neck, check filler compartment is clean no grit blocking hole.

 

As said you really need a fully scan report, perhaps even live data, to be pointed in the right direction as these cars are so complicated.  The scan tool needs to be VW appropriate and the program fully up to date for your model and year (or VIN) and the car battery (and if appropriate scan tool battery) are not low in charge otherwise inaccuracies can appear.

 

What fixes have you tried?

 

30 minutes ago, nta16 said:

Have you checked the petrol cap fully seals fully?  Make sure there's no grit or muck on cap or neck, check filler compartment is clean no grit blocking hole.

 

Are you serious?

4 hours ago, J.R. said:

Are you serious?

You know the answer. 😉

 

Thanks.  AG Falco

Some don't seem to know as much as they think they do - arrogance, ignorance, mix of both (?) - for others. -

 

1K0201557A petrol cap seal ring -

 

https://skodapartsdirect.co.uk/product/skoda-fabia-hatch-2014-21-fuel-cap-seal/

 

https://www.lllparts.co.uk/product/1K0201557A/seat-1k0201557a-seal-ring

 

 

 

On 19/02/2025 at 08:28, Jazajon said:

I make sure the petrol cap is secure every time. 

Just to confirm you tighten the fuel cap until it can go no further and gives audible clicks?

 

14 hours ago, nta16 said:

Some don't seem to know as much as they think they do - arrogance, ignorance, mix of both (?) - for others. -

 

1K0201557A petrol cap seal ring -

 

https://skodapartsdirect.co.uk/product/skoda-fabia-hatch-2014-21-fuel-cap-seal/

 

https://www.lllparts.co.uk/product/1K0201557A/seat-1k0201557a-seal-ring

 

 

 

 

I know that whether the cap is fitted or not, whether it has grit under the seal, whether it is tightened correctly is not going to create an engine warning dashboard light.

 

I also know that you revel in drawing in new and naive posters to your verbose flights of fantasy.

 

 

Engine light and OBD were about emissions, fuel fumes out of a leaking cap are emissions too.

 

@Jazajon a scan tool report with error codes may confirm this, you could also check the cap tightens to where it can no more and gives the clicks and this doesn't happen too soon or it might be a faulty cap.

 

https://www.volksmasterltd.co.uk/check-engine-light-on-dont-panic/

 

2107 VW Golf GTi owner  https://www.golfgtiforum.co.uk/index.php?topic=285876.0

 

More modern cars - https://www.volkswagen.co.uk/en/owners-and-services/my-car/warning-light/fuel-warning-yellow.html

 

The comedy gets better by the minute, sensors to detect fuel vapour from a incorrectly tightened fuel cap triggering a MIL light 🤣

 

You do realise that the fuel tank is vented dont you?

Actually, ummm, you're actually putting something reasonable for a change, OK, so which cap are they refereeing to here then?

 

"Common Issues That Trigger The Check Engine Warning

There are many problems that can cause the check engine light to come on. It could range from minor issues like faulty fuel caps to more serious problems.  In a majority of cases, it has to do something with the air intake, fuel supply or the exhaust system.  Some common issues are given below.

 

1 The fuel tank cap is faulty or loose. Until it’s fixed, you will lose fuel due to evaporation from your fuel tank even when the engine is off.

  .   .   .   " 

https://www.volksmasterltd.co.uk/check-engine-light-on-dont-panic/

 

Tanks are vented. 

Caps seal so that when the vehicle is upside down the fuel is not escaping from the filler pipe / cap. 

As someone who has suffered a similar issue, the fault code was P0442 - EVAP Emission Control Sys

Looked here: https://www.autozone.com/diy/diagnostic-trouble-codes/p0442-evaporative-emission-control-system-leak-detected and a couple of videos on YouTube and tried clearing the code and cleaning the filler cap and top of the filler neck as many people suggested  (I was sceptical it would make any difference, but it's free and easy to do). Three months on and several tanks of fuel and the error code hasn't returned. On the occasion it happened I may not have tightened the cap until I got it to click, since then I've stuck to a minimum of 3 clicks at each fill up.

 

The code I got seems to be related to the Evap system not sealing when the car tries to pull vapour from the fuel tank and into the inlet manifold.

 

The OP should have the fault codes checked full stop.

 

A non secured filler cap if it were going to cause a 0442 error would show up as soon as the engine was started and not while running after half a tank, however if he has overfilled the tank several times then the charcoal filter will be clogged with fuel which could conceivably prevent the tank from drawing in air to replace the volume of fuel used causing a depression in the recovery system, this could plausibly be outside of the operating limits of the pressure sensor if one is fitted.

@Polar yes evap as I found here - http://wiki.ross-tech.com/wiki/index.php/16826/P0442/001090

 

IIRC on other makes, models a "gas cap" issue can cause a difficult or non-engine start but that might be those with flap to seal quick fill Yankee cars, I forget.