Hi, Looking for some advice so hope I’ve posted in the right place. Apologies if not.  I’ve had two fault codes from my cheapie vag com cable and the vcds-lite app on my 2001 1.4 petrol Fabia.  Engine management/exhaust system warning light came on yesterday for no apparent reason.  Code was 00818 which from the wiki seems to be the evap outlet temp sensor.      I will replace it using the guides and my Haynes manual but I wondered if there’s an explanation for the weirdness.  Climate control has never worked on cold, it just does varying degrees of hot on the blower.  Compressor seemed to work, there was a little increase in revs when I pressed the AC button.   But since I got the light and fault code the damn thing works perfectly.  Ice cold air on low, nice hot air on hot.   Any reason anyone can think of why that should have happened?!

I’m quite new to car maintenance and knowledge but I’ve learned pretty quickly and I can’t find anything which might explain this, and my overall knowledge is pretty poor. 

Thanks! 

Speculation: Once the evap temp sensor is giving weird enough numbers that the HVAC module flags it as faulty, it starts to ignore it and work with 'estimated data' or something? Before this it may have been disabling the A/C  to protect the evaporator from freezing, based on dodgy data?

 

I'm a little surprised that this brought the EML on though, were there no other codes?

 

 

Oh there were other codes! The engine coolant temperature sensor is also banjaxed, part ordered and on its way.  I imagine that was sufficient to get the EML light on?  I was just intrigued by the result for the evap temp sensor and the sudden decision on the part of my ancient Fabia to suddenly kick the aircon into working mode.   Thank you for replying. 

 

This forum is a wonderful resource for people like me.  Really great.  I bought my Fabia three years ago for £600 when my Astra died a death.   I thought if I could get six months out of it I’d be doing well.  Thanks to the amazing knowledge on this forum and the kindness of members posting guides and information I’ve replaced the oil pressure sensor, sealed the door carriers, swapped out the stereo and got the jet to the rear windscreen working.  You’re all legends.

Yeah, CTS would put the EML on, when sufficiently out of plausibility (which is a loooong way I should think).  Consider changing the whole thermostat housing with a genuine replacement, unless the thermostat has already been done. These come with thermostat and coolant temp sensor pre-fitted. Part number is 047121111S, I believe.