Hi all,

I am a recent skoda owner and am driving a 1.4 16v 2001 fabia. Recently the oil light has been coming on intermittently, flashing fora while and then going away again.

It happens more when the oil level is lower and/or the engine is hot.Ive changed the oil, tried using higher viscosity oil and changed the filter with no noticable effect.

It happens at any rev count (not necessarily idle) and seems to happen slightly more on motorways (but perhaps thats just when the engine heats up properly).

There doesnt seem to be any particular pattern to it otherwise. The car has some pretty... 'eccentric'... electrics at the best of times but as I say this does seem to have some mechanical basis.

do I need a new oil pump? Is it elecrical? Has anyone else had this problem?

thanks a lot in advance!

Sorry, forgot to mention, have done 90k miles

Now ive tried unplugging the oil pressure warning light switch... and when its unplugged, the light doesnt automatically switch on... is that normal? I would have thought with no signal from the switch the light would flash non-stop...

Please help!

When did you last change the oil filter?

Now ive tried unplugging the oil pressure warning light switch... and when its unplugged, the light doesnt automatically switch on... is that normal? I would have thought with no signal from the switch the light would flash non-stop...

Please help!

Try raising the revs above about 1500. 

 

Here's something found via a search engine with the search term Mk1 Fabia oil pressure warning:

 

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Function of dynamic oil pressure warning system if oil pressure low

 

The oil pressure switch is opened when pressureless and closed when the switching pressure is reached.

 

The oil pressure warning is activated for about 10 seconds after the ignition is switched on („terminal 15 on“). Activation delay of oil pressure warning system: about 3 seconds. De-activation delay of the oil pressure warning system: about 5 seconds.

 

Test warning light

 

After the ignition is switched on and the engine is not running, the oil pressure warning light in the dash panel insert must come on for about 3 s and then go out. The check is ended when the engine is started.

 

Warning criteria

 

The visual oil pressure warning is switched on (oil pressure warning light flashes) and the warning buzzer sounds 3 times as an audible warning if at least one of the following conditions exists:

 

 „Ignition on“, engine not running, oil pressure switch closed.

 

 Engine speed above 1500 rpm, oil pressure switch open.

 

–  At an engine speed above 5000 rpm^-1, the oil pressure warning is not cancelled; not even if the oil pressure switch is closed. The oil pressure warning is cancelled below 5000 rpm^-1.

 

–  If the oil pressure switch is open for only 0.5...3 s at an engine speed above 1500 rpm, this is stored in the combination processor of the dash panel insert. If this condition occurs 3 times when the engine is running, the oil pressure warning is immediately activated and is not cancelled below 1500 rpm^-1. The oil pressure warning is cancelled once the oil pressure switch is closed for more than 5 seconds at an engine speed of more than 1500 rpm^-1, or if the „ignition is switched off“.

*********************************************************************

 

When you disconnected the wire from the pressure switch, was there any sign of oil oozing out around the electrical terminal?

Thanks so much guys,

 

@rbaldwin, oil filter replaced along with change of oil and 'flushing' about 500 miles ago. This problem was happening both before and after the change

 

@wino, the rev count thing made the light turn on when disconnected. I've now replaced the switch and gone for a drive but I'm still getting an intermittent flashing oil light. There was no sigh of oozing or oil residue around the switch before i replaced it.

 

 

When I was talking about the electrics being eccentric, what I meant was that the rev counter and coolant temp gauge drop to zero every now and then (always together). When this happens for over 3 seconds, that's when the oil light comes on, and it goes off when they come back for 5 seconds or more.

 

I thought this was a symptom - the electrical signal from the oil light causing some dodgy connections somewhere - but is it possibly a cause? i.e. the oil light comes on because it thinks the engine is on but revs are at 0?

Edited 3 May, 201412 yr by timlovatt

Update, incase I have any avid readers, excited about my next installment! 

 

I've been trying to eliminate things it could be. Firstly, I'm not sure it's an oil pump failure because:

a) It's sporadic and can go away for minutes at a time

b ) there's no noticeable change in operating temperature, the needle (when it's working) just hovers around the middle/normal range

c) there's no noticeable extra noise from lube-less bearings or lifters.

 

(1) Would i experience any of these symptoms if the oil pump was wearing down/faulty?

 

(2) I've read here: http://www.briskoda.net/forums/topic/197192-instrument-panel-goes-dead/ that a dodgy spark plug can cause electrical chaos?! Has anyone else experienced this? Crash_Bandicoot, if you're out there, it would be great to know which parts of your dashboard went on the blink first?

 

(3) My other option is if the earth for a particular group of circuits is loose/dirty - can anybody tell me where the earth for the rev counter/temp gauge/EML/oil pressure switch is? I've tried following the wires and it seems to be the one next to the battery - can anyone confirm that it's the same one for all of the above?

 

(4) Unless it's worn bearings, but surely worn bearings wouldn't give such sporadic readings? as I say, it happens at high and low revs, high and low speeds, short and long journeys. 

 

Anybody got any ideas? Or better still a diagram of where all the wiring goes inside the engine bay?

Edited 3 May, 201412 yr by timlovatt

Orrrrrrrrrrrrrrrrrrrr...

 

(5) What symptoms would I look out for if the oil pressure relief valve was dodgy?

Orrrrrrrrrrrrrrrrrrrr...

 

(5) What symptoms would I look out for if the oil pressure relief valve was dodgy?

I think that would be more likely to cause excessive pressure at high revs, rather than inadequate pressure.

 

One approach you could take to isolate the oil pressure switch function from the rest of the electrics might be to disconnect it from the loom, then wire a multimeter set to read resistance, to it and chassis ground via long leads so that the meter is inside the cabin. Go for a drive that would typically trigger the warning circuit, and see whether your meter goes from zero Ohms to infinite at any point while the revs are above 1500 (i.e. when it shouldn't). If it doesn't you may be correct about it being an electrical fault, if it does, you're probably not.

 

Edit: An assistant to watch the meter while you concentrate on the driving would seem to be a sensible approach.

...@rbaldwin, oil filter replaced along with change of oil and 'flushing' about 500 miles ago...

The two most likely causes are the oil filter (which you have changed) and a partially blocked pickup/strainer for the oil pump. Whilst they don't get blocked as often as other models, the AUA/AUB engines in particular do suffer from this.

I think we are making progress! Very, very grateful to you both for your advice, thanks for taking the time out to reply!

@wino, you're on to something there, although sods law came to haunt us. I tried your (very clever) idea and the resistance just sat comfortably around 1kohm. Not quite the zero we were expecting but definitely no fluctuations. Good news!

However, I then turned the ignition off to reset the light and wanted to just sit in idle and see if the light came on with the switch unplugged, that would seal the deal that it was the electrics, but I sat there with the engine running for half an hour and even reconnected the switch and went for a drive - nothing happened! No light, no dodgy rev counter, nothing. I think we may have fixed it by thinking about it so much...

@rwbaldwin - thanks so much for your insight, knowing what is more common is invaluable. Ill keep playing with the ohm meter and if its looking even slightly mechanical ill get the pump intake looked at.

thanks to both of you again, ill let you know how it goes tomorrow!

Update: the resistance doesnt change from the sensor at any point even when the rest of the stuff is going mental.

also, when its really playing up, the oil light will come on in idle... way below the minimum 1500rpm at which it is supposed to flash if the switch is open.

tentative conclusion: the tachometer electrics are making the ECU think that the ignition is on, engine is off and pressure switch is closed - hence the flashing....

next question is... where on earth are the tachometer electrics?! Haynes seems a bit useless on this one.

its a rollercoaster isnt it?!? I know all our readers are excited!

To add to the excitement, here's a video of the disco that is the dashboard:

 

https://www.youtube.com/watch?v=-d34YHi1zPg

 

Although for some reason the audio sounds like a train, that's not what the car sounds like

IIRC, the oil pressure switch is a simple 0.7bar switch. On early Fabias, the dash insert has a simple time lockout, so if you crank for long enough without the engine starting, you will get the warning.

The way it's tested is to tee it with an analog pressure meter. The pressure should be 2bar at 2000rpm and never more than 7bar. The switch should close below 0.7bar. Without the meter, you can't tell if it's the switch or low oil pressure.

Thanks a lot rwbaldwin, I'll pop in to a mechanic and get the pressure read manually on Tuesday.

 

Thanks!

One more quick one - if it is a clogged intake screen for the oil pump, how would I go about un-clogging it? 

 

Thanks

One more quick one - if it is a clogged intake screen for the oil pump, how would I go about un-clogging it?

Thanks

You would need to drop off the sump. It's not a difficult job and not too messy provided you drain the oil first

Here is a 'How To' for the Octavia Mk1 http://www.briskoda.net/forums/topic/191103-how-to-vrs-pick-up-pipesuction-pipe-replacement/ It will give you an idea of what's involved.

To add to the excitement, here's a video of the disco that is the dashboard:

 

https://www.youtube.com/watch?v=-d34YHi1zPg

 

Although for some reason the audio sounds like a train, that's not what the car sounds like

 

Wow that's pretty mad. Seems like some kind of intermittent connection going on there. Maybe the cluster printed circuit has a bad solder joint or something?

Another update for everyone - wooohoooo!

 

Took it to a mechanic who took the oil pressure reading mechanically - absolutely no problems, exactly as it should be. Mechanic said it must be some kind of electrical problem caused by corrosion. Corrosion increases the resistance so the full, stabilised 5v doesn't get through to the sensors, so they don't have enough power to send OK signals back to the ECU. When the engine heats up, the resistance increases further so the problem is compounded.

 

@rwbaldwin - thanks for your advice, I'm very pleased I have got the mechanical thing done because now I know I'm not wearing down the bearings more than I should!

 

@wino - your electrical test was accurate! woop!

 

@TMB - yep, pretty weird right! It's some kind of bizarre electrics problem, probably behind the dash, which apparently makes it difficult to replace as it's all wired in to the immobiliser and has to be reprogrammed by a skoda dealer. 

 

 

NEXT STEP - does anyone know where I can find a decent resource with circuit diagrams and where connections are for the fabia mk1? Haynes is pretty weak on this and I wanna know where to start cleaning connectors!

 

Thanks!!!

Internetz haz wiring diagramz. See most recent post of this thread.

In case anyone reads this in the future, I think I have finally found the problem (after 3 months!).

 

Some oil had gotten into the spark plug socket and whilst the plug itself was functioning normally the oil was causing the electrics to go haywire, sending out voltage spikes all over the place. Cleaned it out with compressed air and a cloth, changed the spark plugs and it finally seems to have solved the problem.

 

Thanks to all who have helped!

 

Tim