UK-POLOS.NET - THE VW Polo Forum

Hi all I’m new to the forum, I need some urgent advice for an idling problem on a 1996 (P reg) Mark IV 1.6 Auto.
Reading the forum get the impression it’s a very common fault with polo’s esp on the mark IV. My problem started to happen after the old battery had to be replaced with a new one, as the old battery went flat (but not totally) a few times.
The idling problem occurs only after the engine is warm, not on start-up. Basically the revs drop in a regularish pattern (say every 15-20 sec) but never to the point of stalling (not yet anyway). However it doesn’t suffer the high revving that others have talked about. Also there arent any noticeable flat spots at speed. The problem also comes and goes. But either way its super irritating

Anyway I had the diagnostics done at non official VW specialist who use the bosch system and got the following error codes. ( ive written it exactly as I got it on the printoout)
*********************************************************************************
Control module diagnosis VW AG4 Error memory
0206 throttle valve potentiometer – No Signal

0221 Transmission intervention – open circuit/earth short
No. of errors 2


0214 Power supply signal to low
No. of errors 1
Control module diagnosis VW AG4 Error memory
0206 throttle valve potentiometer – No Signal

0221 Transmission intervention – open circuit/earth short
No. of errors 2

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

I think the ‘0214’ error was cleared, But the throttle valve potentiometer error sounds like it’s the key, can anyone confirm this???

Prior to the diagnostics I tried the battery disconnecting trick for 30min too (well I disconnected the neg only anyway) but that didn’t seem to make any difference. Did I need to disconnect the positive also? Also I understand it could be that the throttle body needs to be replaced/cleaned, or change the Temp Sensor etc???????

The polo is actually my mums car, she’s a newish driver and she’s disabled so she can only use her left foot for the foot controls. So this problem is making it even trickier for her to drive it, especially as she leaves in Drive at traffic lights – the problem is much more noticeable when idling in gear.
Ive booked it into another garage for Monday who want to charge to do the diagnostics again and then what ever else for any extra work! if theres a quick check/fix I can do so that I can avoid taking it please let me know ASAP.

Thanks in advance
(for info im in the leicester area)

Seems that most idle speed problems are caused by the throttle body not working as it should. I had mine taken off stripped and cleaned then re-calibrated to the ECU, now it's fine for another 4 years or so. Many firms would have just ordered a new assembly but I was a little lucky finding a competant garage! I had similar fault codes to yourself although the symptoms were different, mine was revving too high, the throttle pot was showing errors because dirt was stopping the butterfly valve from returning to rest - even though from the outside it looked clean as a whistle. Not sure about Leicester but when I lived in Nottingham there were a couple of good places for tuning - Peacock and Purvey in Chilwell and D&B Carbs near the Notts County ground, you're right to choose a Bosche specialist. Good luck!

I've just got my polo and the tickover wasn't 100%. When i had it in the garage the other week, i took off the throttle body and cleaned it out (gets gummed up round the butterfly, common prob)

Stuck it back on and got my mate to reset the base idle etc with his nice snap on machine!!

Now runs like a dream.

As previous post said, i bet VW would say you need a new throttle body, just cause they wouldn't be bothered to clean it out!

Hi Blackone/phatman, many thanks for your replies. Looks like I should just ask the garage to clean the throttle body and get a ECU reset then? Just to be sure what exactly should I be asking for – an ecu reset/ or an idle reset after the throttle body clean??? I’m not sure about the terminology here.
Blackone when say and the tickover wasn't 100%, do u mean that the revs dropped on a regular pattern like my mums or it revs fluctuated up and down??
Im still a little concerned that cleaning the throttle body might not sort the problem because of the fact that the engine isnt revving noticeably high, just dropping, so im wondering if this is a different problem? Phatman did say his problem was that his problem was that it was revving too high.
Btw the polo has done 58k miles, I’ve read a few posts saying that using 10kBoost and/or shell optimax petrol can help clean all the cr&p out which might also help sort the problem, any thoughts on this??

I'd only had the car for a week, and its my wifes car so hadn't driven it too much. The tickover was a little low for my liking although it never stalled. Not sure if it was labouring or not, although it may have been. It sometimes wouldn't start first time as well.

Although the car had been regularly serviced by VW before i got it, i wasn't happy with the things they hadn't done. So i wanted to change plugs air filter etc (that they hadn't done fro about 25k miles)
When i was in the garage doing this, my mate (full time mechanic) noticed the throttle body and said was i having tickover problems. As i said kind of, he suggested that i cleaned it out (as it was a common problem) and then reset the base idle.

Trouble is, these problems could be caused by a number of things. Our car is fine now.

A good garage should be able to find out whats wrong with your car relatively quickly. Might be worth taking it to an independant VW dealer as they will charge you less than a main dealer, but should find out what your problem is quicker than a general type garage

You could try and clean it with some carb cleaner first - mind you don't get a face full of the stuff though! Quite a lot of dirt came out of the butterfly spindles on mine - but it needed stripping because there was dirt inside. Afterwards the butterfly had to be reset with the ECU, basically you tell the ECU that when it's closed the pot is giving 'x' volts (idle) and when fully open 'y' volts. It's not the ECU that needs resetting.

s79 wrote:Hi Blackone/phatman, many thanks for your replies. Looks like I should just ask the garage to clean the throttle body and get a ECU reset then? Just to be sure what exactly should I be asking for – an ecu reset/ or an idle reset after the throttle body clean??? I’m not sure about the terminology here.
Blackone when say and the tickover wasn't 100%, do u mean that the revs dropped on a regular pattern like my mums or it revs fluctuated up and down??
Im still a little concerned that cleaning the throttle body might not sort the problem because of the fact that the engine isnt revving noticeably high, just dropping, so im wondering if this is a different problem? Phatman did say his problem was that his problem was that it was revving too high.
Btw the polo has done 58k miles, I’ve read a few posts saying that using 10kBoost and/or shell optimax petrol can help clean all the cr&p out which might also help sort the problem, any thoughts on this??

Just an unpdate,I thought id be really clever and try some optimax and really thrashed it just to see if it might help but its definately made it worse after revving the nads off it it started to cut out/stall (dont think it was the rev limiter tho). So i restarted it and it was ok but the idle problem definately more apperent now.
Some more info, ive never noticed the temp never to go over 90 degrees no matter how hard you drive which seems odd to me?? Does this imply a temp sensor issue???
Ive also noticed that the warm idle speed is only 500rpm which seems low doesnt it? also when the idle drops there is very little noticable drop on the tachometer, and the more i think about it, the more think i actually feels like a misfire rather than a drop in revs, but im no expert.
Anyway looks like im gonna have to take it into the garage tommorow and get the throttle body cleaned on the first hand and hope that its nothing else

...oh one more thing, is it worth me asking the garage to change the temp sensor before anything else? (ps is sensor or sender?)

Got a problem with my idling now, its very noisy and not like a diesel this time, just ticking over very loudly but still at 850rpm or so.

Any ideas?

I cancelled the visit to the garage in the hope I can find a quick fix.
Anyway can someone please confirm that the temp sensor often talked about as a fix for idling problems is the coolant temperature sensor found near the thermostat? (as on page 3-5, fig 6.10a in the haynes manual)
Also can someone confirm what the temp sensor should look like, I’ve a pic of one which looks like the one I was gonna buy yesterday here:

http://www.autopartsauthority.com/speci ... parts.html

but I backed out cus I wasn’t sure it was the right thing. Should it come with the outer wiring housing??