Car came in with rough running from cold code read vehicle and p0115 came up but as it was not playing up by the time I got the car as it was still fairly warm I decided to call the customer and explain what was coming up and explained I would not be happy fitting the sensor not seeing the fault with the car although I did think it was very likely to be the temp sensor (WRONG) he agreed to leave the car overnight for me to look at in the morning. In the morning I struck up vehicle and it would not idle or run very well as i looked at coolant temp in live data it was at 56f which i thought was ok so then started looking at the rest of the data and to my surprise air temp was at 156f so my first though was that my scanner must be at fault so grabbed autodiagnos to get same results so unplugged map sensor to make sure wiring was ok which it was after air temp now read -22f so i changed map sensor all was fine customer called in today to say both mornings he has had the vehicle back it has struck up fine.
Regards
Carl

p.s sorry for long post but even if i got same fault in again i would use this same method to diagnose this fault as next time it could be temp sensor

Nice one, this is a commonish fault I think, I had similar and spoke to Alex Walker about it, he had also had this fault and changed MAP sensor and I did on the one I had, all sorted.

Hi Carl, I had the same problem. Fault code indicated coolant temp sensor, which had alresdy been replaced by another workshop. Live data displayed a believable coolant temp, but a wildly inaccurate air temp combined with an inaccurate oil temp. I could not find an oil temp sensor. I wondered if without oil temp sensor, ECU estimated oil temp, giving favour to air temp on a cold engine. Then, going on the basis of two to one faulted the CTS. A new air temp sensor (part of MAP sensor) returned all readings to expected, and fixed problem. Tom

Greetings and seasonal salutations!

I find this interesting. I was called out to a garage today with a Punto with exactly the same problem plus poor starting. OK, it was a 2007 Punto 1.2 8v (not the Grande variant). Having remembered this post (thanks Carl) I was obviously forearmed and noted that the garage had already changed the Coolant Temp Sensor. No fault codes were present but the Air Temp Sensor (ATS) indicated 45c which patently was incorrect. Now this vehicle has a separate Air Temp Sensor and not incorporated within the MAP. This for some reason is at variance with my Autodata disc. By disconnecting the ATS the vehicle started immediately and ran perfectly.

The reason I found this interesting was because I always perceived the ATS as a minor sensor which only slightly trimmed the fuelling I wonder why for this vehicle it now has great significance on the cold start and running of the vehicle? If it had not been for Carl's post, I would have been scratching my head as I would have ignored the ATS reading as inconsequential.

Regards

Pete M

Morning Guys, P0115 coolant temp sensor Yes it's nearly always Map sensor fault. Another thing to look at is when you turn Ignition on and the temp gauge sweeps across to hot. This will set P0115 unfortunately dash problem.

Keith