More bloody fault codes!

[Cle0dy]

So the other night there i was out a drive, nothing too crazy.. Just sitting in 5th gear at a steady 60mph. Next thing the Engine management light came on.

The car has been running a treat since my last EML issue which was fixed by replacing both o2 sensors (and some top notch advice from RUM4MO.. Thanks again mate!)

Just back from the mechanics today to get the codes checked and i got these back

16804 - Catalyst System; Bank 1: Efficiency Below Threshold

16687 - Cyl 3 Misfire detected

16556 - (didnt get this bit.. Sorry)

He reset them and said it shouldnt be much to worry about if the car is running fine and if it does play u to just go back and see him. Im just hoping its not the Cat. thats about to go :/
Its due an MOT in april as well and i want to be prepared if i need to shell out money to fix stuff.

Anyone have any ideas what these codes mean?

Thanks!

[RUM4MO]

That is a buggar - but you know that already! Did you get genuine VAG lambda sensors fitted - ie both S1 and S2 (or same as NTK ones)?

Fault code 16804 is for "fuel trim rich" - it could follow that if this is the case, then the cat system would have a bigger problem cleaning up the exhaust.

Fault code 16687, being cylinder 3 misfire - is it misfiring due to the rich mixture or a fouled plug or failing coil?

Fault code 16556, being catalytic system efficeincy low could mean duff cat(s), or if the lambda sensors are not exactly the correct parts, then the first one is not regulating the incoming mixture correctly and the cat(s) can only do so much work so the monitoring lambda sensor is thinking that the system efficency is low - or if the monitoring lambda sensor (S2) is not genuine, (or same as NTK one), then the same problem might exist.

I'm assumming that aircleaner, plugs and engine temperature sensors are all good.

I think that if this comes back then you need to involve a good VAG specialist.

Final thing is, internet "talk" also includes possible need for an engine ECU update to stop this happening - but that would only be true on this engine if there is an oustanding update available.

All a bit hit or miss I'm afraid - maybe not much better than me not posting - sorry!

[RUM4MO]

Right, second attempt to post this, just a couple of other things picked up about this problem, firstly, is your car a 1.2 3 cylinder (I've forgotten if you quoted that earlier):- some injectors can overfuel if faulty, if the engine timing changes due to the chain jumping a tooth then things will suffer generally, some cars have had cat failures but I 'd reckon that in some cases, the cats will have failed due to incorrect or faulty lambda sensors being fitted, faulty injectors/coils etc.

[RUM4MO]

Any update on this problem, or has the fault light stopped coming on?

[Cle0dy]

hey mate, sorry! Havent had proper internet for a wee while.

Aye, problem seemed to be fine after getting the code reset, however it recently came back on a few days ago so i need to take it back AGAIN to get the code looked at / wiped :/ its really doing my head in!

considering possibly going for a new 1.2 bluemotion and getting rid of this thing cause its been nothing but problem after problem

[moxons]

sounds like coil packs or poss spark plugs ?
worth a check