Hi,

I have recently bought a Polo 6n2 1.4 16v, (engine code: AUA) with electrical issues.

I knew there was electrical problems with it before I bought it but I paid next to nothing for it so I thought I could sort out these "electrical problems" then use it as a daily driver. I was wrong!

The problems with it were... there was no throttle response & a lumpy idle so the throttle body was replaced (by the previous owner). After an electrical scan (by myself) The fault code stated was P0l06 (MAP Sensor Fault) I replaced the MAP Sensor and it seemed to have sorted the problem but soon after a smooth run, the EPC light came on again and there was no throttle again. After numerous EPC faults, scans and replacement parts that the scans referred to were replaced, the same fault codes (and problems with the throttle being non existent) kept coming back.

 So far I have replaced the MAP Sensor, the Vehicle Speed Sensor, the Crank Position sensor & the cam position sensor. I have replaced the cam belt (just in case a worn belt misaligned the timing causing the ECU to miss the fault of incorrect timing & it wouldn't show up on a scan - & for my own piece of mind)

The EPC keeps reporting the same fault codes repeatedly, even after remedy.

The repeating codes are...

P0l06 - (Map Sensor)

P0501 - Vehicle Speed Sensor A Range/Performance

P0170 - Fuel Trim Bank 1

P0343 - Camshaft Position Sensor A Circuit High Bank 1 Or Single Sensor

 

After numerous tries to fix these problems, the problems keep coming back & with new fault codes such as ..

P0322 - Ignition/Distributor Engine Speed Input Circuit No Signal.

I hope someone out there could assist as I have even checked the wiring loom for faults and there seems to be nothing I can find to cause what is happening with this near mint 6n2.

Thanks for any & all replies because I'm not going to let this Volkswagen become a hatred in my life. I've always loved Volkswagen and I don't want this 6n2 to taint my love for them.

10 hours ago, Gooly said:

Hi,

I have recently bought a Polo 6n2 1.4 16v, (engine code: AUA) with electrical issues.

I knew there was electrical problems with it before I bought it but I paid next to nothing for it so I thought I could sort out these "electrical problems" then use it as a daily driver. I was wrong!

Clean all the 'earth' connections.

Yeah, I have cleaned and copper greased all major earth connections under the bonnet and even taken the dash apart to try and find the looms earth's connected to the bulkhead but couldn't find any. I suspected it might be an earth because the fuel guage was being erratic while the throttle was being intermittent one time but I just can't seem to determine which wire might be the culprit. If it is an earth wire it only seems to present itself when I take it for a quick drive when all seems ok & I think I have fixed the problem, then goes back to having no throttle and lumpy idle. 

Thanks for the fast reply.

I was hoping someone might have had similar problems and could point me to what to look at next. Apart from pulling out the entire loom, I don't know if there are common wires or components that can get damaged that could cause the problems I am having.

 I know the loom wire insulation is made from soya so is prone to cracking with a bit of age so that could cause all sorts of problems today.

 

I have loads of old VW looms so I'm thinking about taking the entire loom out and replacing the whole lot with a rebuilt loom but that seems a bit extreme but may be necessary if I can't find the little bugger that's causing all these problems!

On my old Ibiza with the AUD 1.4 8v I had a recurring EPC light and cleaning the MAP sensor sent the problem away for a while, but it returned but no fault codes latched, on close inspection I did find two vacuum pipes from the throttle body to the PCV were split, replaced them with silicone pipes and again it went away for a while but did return, then I checked the operation of the PCV and it was faulty, replaced that and the fault never returned 

 

Thanks nige8021, I'll have a look at the PCV valve tomorrow then :)

I have checked the vacuum pipes and they all seem fine but I was going to replace them anyway for peace of mind and they are not that expensive anyway.

 Some problems I did find in the wiring loom were the looms that feed the doors electrics are degraded and cracked on both the driver's door and passenger door shuts but they are constantly being bent with the doors opening and closing and it shouldn't be much of a problem replacing those. I don't think that is the cause of the problems with the cars electrics anyway but for peace of mind I'll fix them soon with more reliable wires.

 I have also removed and cleaned the egr valve and components as they were very badly clogged with carbon but not fully clogged up. They are immaculately clean now.

 

 I'm not going to give up on this car. I have never let a car beat me before and I'm not going to let this one beat me either! Lol! 

 

I replaced all the vacuum rubber pipes (not servo) with silicon £6/m as opposed to OEM £25 ea !!

Yeah, that was the plan nige8021 :) Silicone replacements are definitely the way to go!

 

So....

nige8021 you were right. The PCV valve was faulty so I've replaced that and I have also replaced the vacuum hose to the throttle body. But a problem still persists. The EPC light came on and also after a few minutes of idling the engine management light came on so I scanned it and the code was P0343 - Camshaft Position Sensor A Circuit High Bank 1 Or Single Sensor. I have already replaced the camshaft position sensor because of a recent scan result so I know it can't be that. I have erased the fault code but it keeps coming back.

Also the fuel guage is still being erratic when I take the car for a short (bumpy) trip, and the speed sensor isn't functioning at all even though it's brand new.

The throttle response is a bit hesitant and it has a lumpy idle but the idle seems to sort itself out after warming up.

Since leaving it overnight the (decent) battery has now lost its charge and the car won't turn over leading me to think there may be a short circuit in the loom somewhere but having the relay and fusebox out for inspection recently, I cannot find a fault anywhere! 

I have also removed the fuel tank filter/sensor for inspection but all seems ok with no obvious faults to the wiring and float mechanism.

This is now almost getting on my nerves! Lol!

Have you had a look at the 3 main engine connectors ? might be a bad pin/socket on one of them  

With regards to your flat battery, it is unlikely that you have 'a short circuit in the loom somewhere' - if there was, there would probably either have been smoke/flames coming out of it, or a fuse would have blown.

First of all, I would suggest that you simply disconnect the negative battery terminal and leave it to stand overnight as before. If, in the morning, the engine still won't turn over, you almost certainly have a duff battery.

If it does turn over, you have a 'parasitic drain' SOMEWHERE in the system - It could be as simple as the radio being left switched 'on' or maybe the boot light isn't going out when the boot is closed..

Anything more than that requires a degree of patience in locating the problem.

If you have a multimeter, a fuse bridge (which fits in place of a fuse) and connects to your meter allows you to check what (if anything) is drawing current BUT you may have to remove each fuse, one at a time before you locate the drain. Remember also, that there WILL always be a small drain by things like the ECU and any alarm system that you may have, but anything over about 500 mA should be regarded with suspicion.

I don't know of anyone who sells fuse bridges since Maplins have gone out of business, but there is no reason why you shouldn't make one up, using a blown fuse (for the plug) maybe an old plastic pen (for the handle) some flexible cable with connections for your meter ans some Araldite to hold it all together.

 

Regards

Thanks to all replies. I really appreciate the help.

nige8021, I think you've nailed it once again!

I think those 3 main engine connectors that you mentioned are the ones in the photo I've posted.

I gave them a wiggle while the engine was idling and nothing happened until I grabbed plug 3. I wiggled the plug and the engine stuttered and then hunted, I then pulled it downward and held it down for a second and the engine stalled. After pulling the plug off there was definite wetness and corrosion on the top layer of pins. I've given the connections a quick clean with moisture repellent and I haven't had much time to do much else tonight but after connecting the plug back up the problem of lumpy idle, hesitant acceleration and the Camshaft Position Sensor fault still remains.

 I'll give the pins a proper sanding and clean tomorrow evening but I guess what I want to know is, could this problem of corroded pins in the plug caused other problems along the loom? Could it have damaged the Cam position sensor with the recurring Camshaft Position Sensor fault? Or the hesitant throttle response or lumpy idle?

 nige8021, I have to thank you because you are an absolute diamond!

 

caretakerplus. You are right. I've tested the battery with a multi meter and the volts are slowly dropping while I test it. I guess trying to get this 6n2 back on the road has pushed this new battery into an early grave!

Thanks again for all the help. I cannot thank you enough.

I'll keep you updated with hopefully gratitude.

Those are the connectors, the one for the Lambda sensor wiring is a very common failure with corroded pins/sockets, it won't cause the sensors to fail, but as they are low voltage signals any amount of resistance (corrosion) will cause the ECU to revert to it's stored maps and so you will get strange running and spurious fault codes.

 

What are you using to get the fault codes ? if you are using VCDS/VagCom you can look at the data from each sensor and see if it behaving