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But not as substantial as the last time

M.O.T day gives me the following...

Headlight level is low.

Rear pads, which I knew were getting low anyway.

And Emmisions ! Which has suprised me !

Only failed on the Lambda readings, which judging by the paperwork should be between 0.97 and 1.03. Mine reads 1.16

They didn't really have a clue what the issue was but said, maybe exhaust leak, which they didn't find on inspection, air leak or sensor issue ?

So any advice on things I can get the garage to look at for this Lambda reading ?

Check your OE exhaust (if you still have it) around the welds on the resonators. Mine had cracked and was giving high lamda readings. Replaced with Milltek naturally...

Could also be a cat on it's way out . Did he check the reading on both tips or just the one ?

Only checked on one tip. Passenger side.

Left it running at about 4krpm for about 10 mins which I though a bit much...

The hotter the better to get low readings.

My previous RS6 failed on the emissions test at Dundee Audi. I went and drove the car for about 1/2 mile with the car in second gear at approximately 60mph, took it straight back and the tester hooked it up and it passed. Always worth giving the system a wee blast.

I did take it for a run before going there, but due to it being -2 I couldn't really give it any stick

I really hope it's not the Cat... Don't see why it would be ? They don't go very often do they ?

I'm hopeful a service and a good check for leaks in the system should cure things

Yup, cats don't work unless they're warm. That's the point of the pre-cats. Closer to the engine they warm up quicker. Give it a good thrashing then ask the tested to do emissions first.

What do the car's lambda probes read? If they are not complaining and the car is failing emissions then it seems likely that one or both have failed.

Lambda reads air fuel mixture , they had a certain amount of tolerance , however I think the car uses a mixture of lambda and egt top work out how it needs too tweek it's running. In the turning world egt a bit more too . On the car the pre and post lambda is checks and altered , though I think the pre is more for the sia side and pre heating the first cat . I service and fresh filters can go a way too changing lambda reading though , so may be worth trying it if you've not already

Doesn’t a failing cat usually give an eggy smell? But yes let’s hope it isn’t that, I’m betting it’s another ‘engine out job’.

A friendlier mot tester could be the easiest solution here

It is possible too get the cats out without dropping the engine , but it does still involve dropping the back end of the sub frame down and a really long extension bar .
Mine is soon too have no cats at all , so I wont have to worry . I work at a place that does mot's now

Ajc wrote: ↑

Fri Feb 01, 2019 6:09 pm

It is possible too get the cats out without dropping the engine , but it does still involve dropping the back end of the sub frame down and a really long extension bar .
Mine is soon too have no cats at all , so I wont have to worry . I work at a place that does mot's now

I was quoted for an engine out job to fit a pair of decats on mine as the specialist was adamant it’s near impossible to remove the bolts without the studs snapping.

Oil change and Plug change and the readings are now within normal levels.

Back in tomorrow for the retest.