UK-POLOS.NET - THE VW Polo Forum

Hey,
I have had a few visits from my Exhaust emissions light at least 3 times in 6 months giving the fault code of:
17584/P1176/004470 - Bank1: O2 (Lambda) Correction Behind Catalyst: Control Limit Reached.
Due to recently having replaced the two lambdas with brand new ones I have turned the light of each time from this lambda code and the car runs great for a month and then the light comes on again saying the same thing.

Only two days ago I was driving along when the engine was cold and going really slow when the exhaust emissions and EPC light came on at the same time. The code mentioned above was present and also there were 2 others that appeared:
16786/P0402 - Exhaust Gas Recirculation (EGR): Excessive Flow
17550/P1142/004418 - Load Calculation Cross Check: Lower Limit Exceeded

Has anyone experienced this? I have looked up the possible solutions on Ross Wiki but I dont know where to start. I dont want to keep wasting money on parts when this light just keeps re-appearing.

Thanks ,

Jollus..

I had they same two lights on dont know what codes but it turn out that the egr valve was shot

This sounds like its getting a bit expensive, maybe try cleaning out your EGR valve and checking that the pipework for it is all clear. I assume that you have VAG-COM or VCDS to let you run adaption on the EGR valve after you clean it. The load calculation cross check code sounds like a MAF problem, so I'd just try cleaning the EGR system first - then see what happens.

Let me guess - hummmm the engine code is BBY?

Yep its BBY. How did you know? lol Right oh then I will start off by cleaning that valve and inspecting it. Where exactly is it under the bonet?

The EGR system really runs from the exhaust manifold to cylinder 4 - so that seems that its down the right hand side at the front. Mayve have a look in the Seat and Skoda forums as they both used this engine. I'm getting a bit worried about all this BBY activity as my wife's car is 2003MY and 57,000 miles and so far, engine wise has only had one coil replaced and the pre-cat Lambda sensor replaced. Good luck!! Maybe fork out on a Haynes book - its not 100% brilliant - but handy.

If it makes you feel better, our engine is a 2002 AZQ at 65k, we've had both these lights on in the short time we've owned it, and have so far had to replace the cat, the throttle body, a thrust sensor, and the EGR valve - none of which was cheap. Running ok now but who knows for how long.

What is a thrust sensor anyway?

"THRUST SENSOR" - I think that description originally had proper techs sniggering - but I think that its what VAG call what some engines now use instead of a MAF metering system. That is an "educated" guess - but it does ring bells somewhere in my small brain! MAF were originally just a hot wire anemometer, then they became more useful when some other bits were added in.

That would make sense... in our case (according to our VAG specialist) it was probably the original problem with this thrust sensor that caused a previous owner or their mechanic to start fiddling with the throttle body and break it. Their bodged repair kept the car running but probably contributed to the early demise of the catalytic converter too (I'm guessing). The EGR valve was just the icing on the cake, going haywire (and sending the engine into convulsions) just as we'd had everything replaced.

I shouldn't even comment on how the car's been running for the last couple of months since then - there's not enough wood around to touch. I'd like to think there's a logic to all this though, and we haven't just bought a cursed car.

I think that I've read on another forum that about 75% of EGR valves that are changed are not faulty, and yes it seems that quite a lot of "fixers" seem to break perfectly good throttle bodies.

How did you know that the cat is was gone? I dont think I will check my EGR valve out judging by what evreyone else is saying. If it made the engine go funny then thats not whats wrong with mine cos my engine always runs perfest even when these lights are on the dash. Its been 3 weeks now and I haven had a sniff off either light but it will be back soon. Its strange how it goes a month and then the light comes on init?

Normally cats cause an increase in temperature - or their inlet is colder than their outlet if they are "working". You can check this easily with an IR temperature probe thing - Maplin might sell one cheaply. Its also handy to detect lots of other problems brakes etc!

for the lambda faults there is an engine ecu update take it to the dealers

yorks GT TDI wrote:for the lambda faults there is an engine ecu update take it to the dealers

That leads nicely on to the next two questions "how do you get to find out if your controller software is up to date?" - and " what prompted each of the updates?"

only way to tell is to run it on a dealer comp online to vw these updates cam from vw when lambda fault were not fixed with parts

Wouldnt leaving it with the dealer for a software update be expensive though?