so here goes, i have a 1.4 16 valve petrol engine code axp, 145,000 miles, timing belt at 125k, doesnt burn oil considering mileage, does about 100km to 7 liters of fuel, so things ive done so far new rear exhaust, fresh oil and filter, air filter, throttle body cleaned, thermostat replaced, i changed the spark plugs for some i had lying around 3 are single electrode compared to triple and one double iridium one, i know i need to buy a decent set but funds are very tight for a week or two and the condition of the old plugs were horrendous the porcelin insulator for the electrode was starting to wear because there was so little left of the electrode itself, cleaned map sensor was very dirty, had egr fault cleaned it and was missing a gasket on the end of the pipe joining to the inlet made one with gasket maker and no fault there since, two window regs, two tie rod ends, two ball joints, tracking think thats it was slightly neglected by privious owner.

 

now my problems are ive epc light one, diagnostics shows up brake light switch code 16955 only, my brake lights are functioning correctly, tried changing bulbs and also replacing switch with a lucas brand one but epc light still comes back within ten miles after clearing code, car doesnt have cruise control anyway if that helps.

 

next one is the car even with the new thermostat takes an age to warm up? normal? temp sensor is ok as far as i can tell.

 

my cars idle is a bit irractic sometimes its ok but has little shake, other times quite lumpy seems best when cold hot idle is a mixed bag. hates being start on a hill facing nose down runs like a proper bag of spanners then

 

i also have a slight power issue at times it goes fine and will pull away decent for a big car with small engine other times it takes an age to pick up speed and to go along with this sometimes after going up hill for a period the car will cut out stall for a few seconds and go again without the need to twist the key but today it needed the turn of the key while losing speed trying to freewheel up a hill not exactly fun! 

 

there are no faults recorded apart from the brake light switch have searched and read loads off various forums but nothing seems to add up to what im experiencing so any help appricated and hopefully i can get this octavia purring again!!

 

 

If the temp sensor isnt a genuine bosch one, that will be the issue the temp gauge. Mine (1.9tdi) didnt read above 70 unless stopped in Downhill traffic for 2yrs... ran like a clock.

 

Erratic idle is probably the MAF sensor. Again get a genuine one not aftermarket as Vag engines dont like non genuine..

 

The power issue could coilpack(s) dying or the mixed bag of spark plugs, esp if they arent gapped correctly. (Also likely to be unhelpful with the idle)

Worth checking all the earthing points etc are in good nick and not corroded causing an intermittent fault..

thanks for the reply, the temp gets to 90 degrees just takes an age to get there but stays there when it gets up to temp compared to my last car a friend recommended blockin half the rad with cardboard to get it to warm up faster but im skeptical.

 

my car doesnt have a maf only map i think and i took it out and cleaned it was quite dirty.

 

i will change the plugs asap maybe today altogether just ive put about 200 into the car recently so funds are tight :( but i gapped them with a feeler gauge prior to fitting to .8 mm will look into earths later too

just an update i changed the plugs and made very little if anything its slightly worse at times, im leaning towards the throttle body but i dont have vag com only hand held at the minute my laptop died sadly couldnt find a vaccum leak also replaced 5 tiny bulbs in the high brake light to see would that help my brake light switch but it didnt, anyone have a part number for the o.e switch mines non oe and i tried a lucas one recently which didnt work either its not communicating with the ecu but is working the brake lights

The temp sensor may be a dual type, one sensor for the gauge and the other goes the ecu.  

 

Two type of brake switch, one is a single switch, yours by the sound of it is the dual switch type, also come in a selection of colours with slightly different actuator. There is an installation procedure to correctly adjust them when installing  (you'll have to look that up)

 

Implausible brake signal error is that one of the dual switches disagrees with the other. If not a broken switch , often its due to wrong bulb types fitted which inject voltage into the brake light circuit. Check the correct brake bulbs are fitted, twin/single filament, correct wattage, correct bulb pin offset position, correct bulb base  config. It is possible to fit wrong bulbs /offset pin bulbs but then the position lamps and brake lamps get shorted together etc.

 

Your ignition coil(s) may be failing or ignition lead with broken core if it has those.

Edited 9 March, 20197 yr by xman

ok so another update, it seems the idle issue is solved (crosses fingers) i cleared faults and disconnected battery for 30 minutes, reconnected battery, turned on ignition for 3 minutes, switched off ignition, started car and left it idle until warm. the car idle at 800 rpm steady. did a test drive circa 10 miles and stopped half way and idled fine. will know more as i use it more, i replaced my two tail lamp bulbs but only one fog is working both tail bulbs are tho weird. if i could cure my epc light on the dash id be very happy i have implausible signal 16955 but both brake bulbs are working from the pedal?

On 09/03/2019 at 09:34, Richiet90 said:

the temp gets to 90 degrees just takes an age to get there but stays there when it gets up to temp

That makes me think that the thermostat may be stuck open.

hi ken no there is a new vemo brand thermostat installed maybe its just because it has a bigger cooling system to my last car more coolant to heat up its probly normal. the car had its nct/mot today and it passed with no advisories happy days if i could cure the epc light it would be perfect