Help!!

Not sure if I'm posting this in the correct website section, but here goes.

Model: Skoda Fabia, petrol, HTP, 1200cc, 2007.

When driving put interior fan on and car losses power, EPC light comes on. Turn fan off, problem remains and EPC light stays on. After resting car for period of time issue goes, light off. The interior fan seems to start issue. Battery, alternator been tested, both OK. Went to garage, who did diagnostic test, couldn't find anything, but said something about throttle body voltage drop. RAC man also mentioned throttle body needs cleaning, when I originally broke down. Have removed, and cleaned. Am not convinced that it is this. Any ideas?

Many, thanks.

PS: After replacing and inspecting throttle body, still have issue.

Edited 10 May10 May by Greycar

Sounds like a corroded earth somewhere thats causing voltage drop when car electrics are under more load. Not sure if the fan and ECU share same earth point. Check the earth nearest battery first under battery tray and check if you can where I think brown wire goes from ECU.

Alasdair

Hi Alasdair.

Thanks for the reply. Have checked negative lead from battery to bodywork and also under battery tray. Both fine.

Will look into lead from ECU unit. Did notice that ECU unit is a little lose where it is located, due to plastic locating tabe being broken. Could this cause a problem?

Thanks.

Maybe as its loose the connector needs reseating or broken wire. My sons fabia is the same but I managed to feed a couple of long cable ties behind the bracket and then round ECU to secure it in place.

Alasdair

Hi Alasdair. Wiring from, to ecu unit looks OK. There are 4 brown wires that are near the ecu unit that are grounded. All are secure and clean. I also secured ecu unit. The only thing I can think to do now is put a new throttle body on because of initial mention made by RAC man, and they also mentioned the throttle body in the garage where I had a diagnostic test done. I'm not convinced that this is the issue though. Any further ideas before I replace the throttle body?

Kind regards.

If you know someone or have VCDS might be worth a scan. VCDS sometimes pings up codes that other readers including garage ones miss before changing TB

Alasdair

Hi.

Have used an OBD2 scanner and a fault code for the brake switch comes up. Have read that this can cause the EPC light to come on, also that it can cause throttle body problems as it's linked to the ECU unit. Will replace this switch first. One nevers knows it may do the job, worth a try as it only cost about £12. If problem persist will fit new throttle body.

Many thanks for your replys.

Certainly on the Mk3, the engine power cuts-out if the brake pedal is pressed while throttle is open - accompanied by a message on the infotainment screen.

Same on the MK1 1.9tdi my folks had. Tried once to clean rusty front discs for MOT by driving with brake on and car immediately lost power and loads of warning lights on. Hope it works.

Alasdair

Hi. Fitted new brake switch and I think that it may have worked. Have driven about 45 miles and in this time have put the interior fan on numerous times to test whether it still starts the issue to occur. Twice when I did this there was a very slight hesitation, which hopefully is just a blip. Time will tell. If the problem resurfaces I will fit a new throttle body. Can anybody recommend a good mid range diagnostic code reading scanner that also adapts throttle bodys on a Fabia.

Thanks for your input guys.

Hi. Brake light switch change seems to have addressed the issues that I was having. See above. As have done quite a few miles without problems.

Now noticed that sometimes if car is put into neutral when slowing, revs fluctuate before settling. Have had this issue on occasions for quite a while. Did diagnostic test and code for engine speed sensor showed. Wasn't showing when had trouble with brake switch. Maybe that fault code was masking it? Has anybody an idea of where this sensor can be located on a Skoda Fabia HTP 2007, and is it hard to change

Many thanks.

Think its on rear of gearbox/bell housing on top . Easiest to get to from under car. Could be a wiring issue to it unless yours is an auto??

Alasdair

Crank sensor is horrible to access and replace - back of engine block below intake manifold right at gearbox end.

Will add a photo shorty.

If it was me I'd be looking to eliminate other possible causes of the behaviour, and not just trusting that the fault code means sensor fault.

Clutch switch malfunction, or air leaks - brake servo vacuum hose always worth checking thoroughly, visually and with fingertips.

Often cracks are found at junctions of hard plastic sections.

Thats different to the one I was meaning. On my sons 1.2htp theres a sensor on gearbox rear top near steering rack. I assumed it was speed sensor but may be wrong.

Alasdair

I guess you mean this dude, just near offside drive flange?

That's a dummy vehicle speed sensor that was where the vehicle speed speed sensor was fitted prior to ABS sensors taking over (around 2002 I think).

Not the same as an engine speed sensor, which is more often known as a crank, or crank angle sensor.

Hi. Had noticed that brake servo pipe did have a split in it, which I taped up as a temporary measure. As far as I can tell can't see how it would still be leaking. But before doing any thing more will get new servo pipe.

Can vacuum pipe, which can be brought on ebay for a good price, be used. As getting it from Skoda is very expensive for what it is.

Many thanks.

Look via oem code online or on skoda-parts or look for a genuine one but used, most of the time is better a good condition but second hand spare rather than a new one but from a cheap brand