lambda? engine management light on

[busterg88]

hi everyone im new to this site i have a standard (atm)1.2e red polo 9n n need some help. the emisions light come on so i bought a gendan £40 code reader it does the trick which told me my cam position sensor was faulty so i replaced that n it was goin well, then a few months after on a freezin morning my engine management light come on and my litle red coolant temp light started flashin and beeping i read the codes and it was fuel trim rich and 16804 i erased the codes and a kept checkin them nothing come up then a few days ago the same happened again but only the 16804 code come up i no the 16804 is a lambda sensor code but ive heard people replacing lambda sensors when this code comes up and it not fixing the problem so dont want to waste money so please help many thanks busterg88

[RUM4MO]

Yes, the Gendan tool is quite handy, I've got one just to keep handy in the boot. Unfortunately, this "cat efficiency" code needs something a bit "heavier" like VCDS to dig deeper and check the lambda probes for aging. The only other thing that gets reported on these forums is that an exhaust leak can also cause this, but I don't know where it would need to be to cause this problem. I had a partially fractured flexi section for a few months but did not get any fault codes logged due to that. Unfortunately there is some history of the 1.2 needing its cat replaced due to this problem - but when you do that its also common sense to replace both lambda probes - so if the probe(s) was(were) faulty then replacing this lot would always end up with the car being sorted. I think that maybe you need to consider the "fuel trim rich" - just to see if the control lambda probe S1 can cause this - then change it. VAG tends to be as cheap as anywhere when I needed to buy one. I think that a lot of the "wrong" mixture problems can be caused by the MAF or whatever device is used to measure the airflow - there are just too many options available for having a first stab at guessing your way out of this problem, but unfortunately your local VAG dealer might also hit you for him guessing what to do next! Sorry!

When the lamda probe failed on my wife's Polo 1.4 SE the listed codes included "bank 1S1" in their description, as did some different codes on a friends wife's Golf 1.6 SE - in both cases replacing the pre-cat lambda probe solved the problem - remember in your case, the logged code does not mentionn S1 or S2.

Maybe have a look on http://www.briskoda.net and http://www.seatcupra.net to see what problems their 1.2 engines have been having (that's Fabia section and Ibiza section).

[Ricochet]

on the way to have the big front console bushes replaced the engine management light came on'
The garage printed of the fault code foc but wanted ~£55/hr to carry out a full diagnostic check.

the print out reads : 16804-Castalyst System;Bank 1:Efficiency Below Threshold
P0420 - 35- 10 - - - Intermittent

the guy said he thought it was probably the catalyst, what do the rest of us think ?

[RUM4MO]

Ricochet, just for clarification, which engine does your car have, also car age and mileage - ta.

[JUV]

For comparison, we had that exact same fault on our 2002 AZQ-engined Polo, and it was indeed the catalytic converter (or "mani-cat" as its known on this engine, as it incorporates the engine manifold).

[Ricochet]

52 plate 1.2S petrol , ithink the engine code is AWY ,or something similar, ~68 000 miles,.

sorry,some of this info used to be on a little signature which I now don't see.

[RUM4MO]

I had a horrible feeling that "1.2" was going to be your answer! Look elsewhere, maybe on this forum, on www.seatcupra.net and www.briskoda.net to see what other people are finding is the root cause of this, there seems to be a lot of guessing on the part of the garages including dealers. There is a real tech (Lummox) on www.briskoda.net, you can ask him questions if you join their "freedom" thing - I did for a year and it was worth it, I've let it lapse though at the moment!

[Ricochet]

Thank you RUM4MO
i will check those sites .

We cleared the fault light and it hasn't come back on (yet).

Garage man thought it would be ~£4-500 for a VW Cat -------aaaargh!!!

The light came on about 2 mths ago and we bought a lamda sensor ( Fuel Parts box and leaflet but with VW/Audi part no on it !) ( <£90 ) but as we cleared the light and it stayed off then we didnt fit it.

No report of increased fuel consumption , which was very noticeable when the coolant sensor went ' not playing anymore',
so we may see what the MOT brings.

ps . £400 for new AR bar , console bushes and drop links !! and no alignment.

[RUM4MO]

Hi, £400 for new ARB and console bushes (without 4 wheel alignment) is a bit naughty, I'd expect them to include the alignment for that money.

Using "Fuel Parts" spares, could be okay, but remember these aftermarket people will always be slow to respond to design changes. VAG tend to use NTK (NGK trading name for Lambda probes and glow plugs) - and they are manufactured in Japan. What really counts is exactly what/who's probe do Fuel Parts use - NTK's is stamped on the lower end of the VAG ones. Actually, if you are really interested (!), there is a semi-technical overview of these engines both the "2 valve" and the "4 valve" in http://www.briskoda.net - itwould have been created by Skoda to pass to the garage techs at this engine's launch time. Your probes would need to be checked for performance before changing the manu-cat as if the pre-cat one is "not good enough", then your next cat's life will be short!

I've mentioned in the past that these little cars do tend to destroy your wallet (been there done that), so all you need to happen now is have a front spring break - that is not very nice! Has your engine had any upgrading of the timing chain fittings/guides - as that might save some money in the long run.

A lot of bad things are said about the 1.2 engines in general - but just to cheer you up, this engine or a variant of it, is here to stay as VW are going to use it in the new Polo as "2 valve" + "4 valve" + TSI'd and that means 105PS I seem to remember (source April VW Driver). For me, I'd prefer a 1.6 16V 105PS if that was possible - but I'll be out of luck as for petrol engines it is = 1.2 2 valve > 1.2 4 valve > 1.4 16 valve (85PS) > 1.2 TSI 105PS) > ?(maybe 1.8T I've forgotten or maybe its 1.6TDI as the top engine in true VAG style - and of course 1.4TDI)

[Ricochet]

RUM4MO,

thank you for all your advice,even if some of it is a bit worrying!

The light is still off ( fingers X'd ).

Timing chains, guides ? no work carried out on these as far as i know , should i be thinking of doing something ?