Coolant Sensor / HC Emissions Question

[SammoVWT]

Evening all,

Hopefully a relatively straight forward one. First things first:

Coolant sensor, does anybody know what colour this should be for a 1.6 AEE? Ive currently got a yellow one fitted, but im led to believe the colours have changed.

Or alternatively the temperature range which this sensor is supposed to operate at for this motor? Ive yet to plug it in and check the reading but thought I would ask first as its related to my MOT emissions.

I have to granny the car to hit 30mpg in town (brim tank mpg test), and im sure it shouldnt be that difficult with it only being a 1.6.

Secondly,

I noticed on my MOT emissions test, that while it passed, the HC levels were elevated from last year at idle. I need to do an oil change soon (later this month), and the plugs and leads are good. I dont have any missfires that im aware of. Not losing any coolant now since ive fixed the hose/tank/cap (so ruling out head gasket).

Last years emission test: CO - 0.00%, HC - 27ppm
This years emission test: CO - 0.01%, HC - 63ppm

Nothing alarming, its just not as low as it was previously, and I wanted to get a second opinion on it.

The question is, could this be related to an incorrect/failing coolant sensor? Oil change requirement? (Although the oil level is 1/4 litre overfull due to a little haste on top up on my part, but will be sorting that in the next couple of weeks - could the oil vapour from the slight overfill be transmitted down the line as HC? (im not sure how likely this is) Or a vacuum/air leak? Or possibly distributor timing/alignment? (not noticed any strange idle behaviour/power loss)

Ive not heard any apparent whistling, the CAT is new and im not seeing any visible smoke being at the exhaust. (there is a tiny tiny exhaust leak after the CAT, but its virtually nothing)

Ive got a feeling its slightly overfuelling due to the coolant sensor, but I will probably pick up one from VW (provided they have stock!) to be sure.

I dont think its desperate by any means. Just was hoping for a pointer or likely causes. I am actually starting to wonder if the car cooled down a little before the emissions test was done.

Cheers chaps ! :beerchug:

[SammoVWT]

Right bit of an update for those who care:

Replaced coolant sensor, the correct one should be a 'blue' vw type. (4 pin)

Part number W6U0 919 501 B - Z4A7D1 Tempsender from VW if anyone should need one.

Was a bit pricey at £34 but worth it for the genuine part.

Car feels much more torquey now (exhaust is noticably cleaner smelling), and after taking it for a bit of a drive, and brimming the tank, the needle has barely moved after 30 miles. So im a happy bunny, its much more what it used to be like now. Rather than 15-30 miles per half notch on the guage.

I will do a brim check mpg after ive finished my work run, but im confident I should be able to save even more on my fuel bill now.

(Decided to replace as I have been doing a lot of short trips this past week due to picking up bits for my new arrival [all is well thanks!] and the fact that every other major sensor/component on the car has been replaced. I noticed that I got 20mpg this week which to be honest considering the weather, is shockingly poor.)

Happy days! :biglaugh:

EDIT: Projecting about 375-400 miles a tank now with urban driving