Had to replace the exhaust gas sensor (bank 1 sensor 4) engine management light on, glow plug light flashing intermittently, and dpf regen light coming on. Vag Com cable indicated bank 1 sensor 4. 

 

Good news is that I would put it at a 'one/two spanner Hanynes' difficulty job. 

 

Requires getting under the car and getting the engine under tray off. So will need axle stands or ramps and torx bits for getting undertray off.

 

If you intend to do this job yourself please ensure you research how to SAFELY put the car on stands or ramps. 

 

Once you are under you can just about get into the sensor. There isn't much room and it can be a bit of a pig to get the sensor which is likely stuck firm, out. 

 

I ended up taking for a drive to heat the car (exhaust) up, and then applying a liberal dose of plusgas pentrating fluid. 

 

I had bought the part from TPS and it cost about £130 - might have been a few quid more, and I don't have the invoice to hand. Part number was 03L90608CC.

 

The sensor I took off had an orange plug, yet the sensor I put on had a brown plug but both parts had a sticker saying 942 around the cable - that and the conversation I had with the cashier at TPS convinced me that I had the right part. Be aware that EGT sensor number 4 is NOT the one that usually goes, but in my case it was - just be sure you are replacing the right sensor. Especially as I suggest using the ring end of a combination spanner so you don't slip off the sensor while trying to turn it - and this will mean cutting through the cable just above the sensor so you can get the ring to freely go over the sensor (obviously once this is done your cable is damaged, so you must be sure you are attacking the right sensor!).  I used a flexible head spanner which allowed me to play with the angle a little - there really isn't much room to manoeuvre. The spanner is a 17mm. 

 

After driving the car to heat up the exhaust remember the exhaust will be very hot so careful not touch the exhaust while you are under the car, while it is hot. 

 

Turn anti-clockwise with a bit of conviction, try not to swear too much while your internal voice says it's never going to come loose and you need relent and drive it to your local garage in a cloak of defeat - it will come loose with persistence. 

 

Once it comes loose it comes out with ease and the new one will screw in with ease, just remember to hand tighten most of the way so you don't misalign the threads. Then finish off with the spanner - this time using the open end of the spanner! The orange plug goes up to the top of the engine bay and is held in place by a series of clips - two plastic and one metal - the metal clip, just lifts up. 

 

I'll try and post some pics

 

sensor with spanner around showing cut cable

 

 

 

showing sensor position in relation to being under the car 

 

 

showing metal clip being held in an open position by screwdriver, so you can see how it opens.

 

 

showing difference in colour between new (brown) and old (orange) sensor both with '942' stickers

 

 

Diagram showing position of sensor (think this is from a roomster or other model than Octy, but thing to remember is that the sensor is the one after the DPF as pictured in my photos)

 

 sensor plug position in engine bay.

 

Hope this info helps someone out. To be honest I took to long to get round to doing this job and probably didn't do my DPF and favours, for the sake of a £130 and an hour under the car - I should have got round to this much quicker, and I would advise others not to hang about. Anyway the sensor is now fitted and the engine light has been cleared with VCDS. Now just the mystery bulb warning light and the airbag/horn warning light to fix... 

Very nice write-up. Engine bay could do with a clean though  :p

Engine bay doesn't look that dirty to the naked eye..

More embarrassed by the state of the upholstery, anyone ever tried steam cleaning the seats ?

to answer my question, steam-cleaned the cloth seats, and they came up a treat - after having some really nasty stains that I'd tried to get out using upholstery cleaner and a brush previously, and failing miserably. 

 

So if you do have cloth seats with stubborn stains, try steam cleaning. 

Just be careful steam cleaning seats, getting moisture into the occupant sensor isn't a good idea.

Tricky bit with identifying temp sensor 4 is its actually the third temp sensor. Technically sensor 2 is the lambda probe, creates all sorts of confusion.

Just be careful steam cleaning seats, getting moisture into the occupant sensor isn't a good idea.

Tricky bit with identifying temp sensor 4 is its actually the third temp sensor. Technically sensor 2 is the lambda probe, creates all sorts of confusion.

True but if they named them Temp sensor 1 and lambda sensor 1 it would still confuse people who can't tell the difference 

I have this issue also but trying to order the part but the number you stated 03L90608CC. Does not come up in any searches, is it missing a digit? The only sensor I can find comes up as 03L906088CC. Is this correct? Don't want to order the wrong part.