High emissions/MOT fail

[GDad]

Hello all,

Had my Toledo ('99 V-plate 1.8 20V SE) MOT'd and it failed on emissions. The CO emissions were approximately twice the limit

Had a new exhaust on their last year and that's been checked and apparently no leaks. Changed my air filter today as well which was pretty filthy. It was done at an Audi dealer so they put it on VAG-COM but couldn't tell me what the codes meant as apparently it's different software? I've been told it may be a lamda sensor or cat, although I got the cat checked at kwikfit (was in there for new tires anyway) and they 'knocked it' and said it seemed fine.
Anyway, I'm trying to find out what the likely cause is of the high emissions. Also I don't know if it's linked but my car has now developed an issue whereby when warm if I leave it for a few minutes and go to start it then it really struggles and the revs go up and down before settling and often stalls, whereas starting from cold is fine.

The VAG-COM codes were printed off for me by the Audi guys and are as follows if they're any help:

17916 P1508 035
Idling system learnt value - upper limit reached.

16502 P0118 035
Engine Coolant Temp Circ
High input - sporadic
Think the second one is that I may have a small leak in the engine coolant as I've had to top it up every 4 months or so due to the warning light coming on.

Any help much appreciated,

Paul

 

[m0rk]

the coolant temp sensor is failling, which means the car thinks it's always in cold start mode. which means more fuel.

which means the cat is on it's way out.

change the coolant sensor (about £17), and change the spark plugs (always works for me) and retest the emissions

 

[GDad]

Thanks very much for your help, will give that a try.
Being a bit thick when it comes to cars, is the coolant sensor the same as the thermostat as I can't find a part listed as coolant temp sensor, only coolant level sensor on eurocarparts where I usually buy my bits and pieces from? Also don't suppose you know where the sensor is, as my flatmate is reasonably good with cars and said he'll change it for me if I can tell him where it is, but I'm pretty hopeless!

Thanks
Paul

 

[silver surfer]

get a genuine temp sensor as non gen seam very poor or reliability