Technical Changing temperature sensors ??

[Jack1708]

Hi all

Is there a guide or details on how to change the temperature sensors on a fiat punto grande 1.4 petrol ?

Thanks

Jack

 

[Andy Monty]

which temperature sensor engine/ coolant or air temperature?

 

[Jack1708]

Coolant please

 

[D4nny8oy]

What's the error code? There's a common issue where the ECU suspects a coolant temp sensor fault ("water temp sensor feasibility"?), but it's actually the air temp sensor at fault (reading too high).

 

[Jack1708]

D4nny8oy that's exactly the fault I'm trying to fix.

For the last two months every morning the car struggles to start, has to be cranked roughly 5/6 times before it turns over and I get the message "excess coolant fluid temperature, stop and turn off engine"

After much reading on this forum and others and speaking to fiat it seemed to point to a software update so I had that done - that didn't work

Fiat said I needed a bigger capacity battery 60ah instead of 40ah so I tried that - didn't work

So I decided to change the very thing the message said : the coolant temperature (sensor). Spoke to fiat and got one for £20, I'd also read there were two other sensors that could be linked to this fault : the "air temperature sensor" and the "map sensor" so I enquirer abut these : £60 for air sensor and £90 for map sensor.

So I've started with the coolant sensor, I've changed that now and will see how it is in the morning.

But you say it's the air temperature sensor that causes this fault ?

Thanks !!

Jack

 

[D4nny8oy]

Yep, the problem is on cold start-up the ECU looks at the coolant and air temp and expects them to both read more or less the same. When the air temp sensor plays up, it tends to stick at 40deg+, but the ECU decides to trust this over the coolant temp which then plays havoc on cold start as it's not rich enough.

TBH, the "Excess rad. fluid temp" message on it's own is usually caused by the voltage drop on cold start (Software update and/or larger battery is the fix). I suspect the repeated cranking attempts are what's affecting the battery voltage now and causing the message to still appear, so fixing the air temp sensor fault should cure all the issues..

 

[Andy Monty]

Danny is that the one built into the map sensor? If so jack there is a guide in the grande punto guides section for replacing it


also check the engine bay earth strap is ok

 

[D4nny8oy]

Andy- I seem to remember some having a seperate air temp and map sensor, and some having the two combined. They're both in the same area, so it's easy to see if there's just the one or two sensors there.

 

[Jack1708]

Well the new coolant temperature sensor didn't work. So ill try the air one now, couldn't see a guide in the guide section but ill have a better look later, don't really need a guide just a general idea of where it is if u happen to know? I think it's on the inlet manifold isn't it?

thanks both for your help its much appreciated!!

 

[Andy Monty]

https://www.fiatforum.com/grande-punto-guides/227405-1-2-1-4-map-sensor-replacement.html

 

[Jack1708]

Andymonty

Thanks for the link, attached is a picture of the same place in my car as the first picture in your guide.

In my car however there seems to be two sensors, I presume comparing the two pictures that the bottom one is the MAP sensor and the top is the air sensor ? So it's split in mine ?

Would you both still recommend changing the air sensor as there split ?

If so I've took the Bosch details on the side can I use them to get a replacement ?

Thanks again

Jack

 

[Andy Monty]

D4nny8oy will know both my gp's have only had one sensor


whilst your at it take a close look at this: (totally unrelated but might as well take a peek)



https://www.fiatforum.com/grande-pu...ater-footwell-rust-brake-servo.html?p=2742527

 

[D4nny8oy]

From what I can remember, and with some sleuthing on ePer and Google, it's the larger, lower sensor for the air temp (item 3 in the pic below).



Googling the part numbers brings up both as being air pressure sensors (helpful ), but I recognise the one with a 'nipple' (71732447) as being an air temp sensing unit rather than just purely a MAP sensor-

http://www.findpart.org/part/fia-71732447
http://www.findpart.org/part/fia-77363792

... and a Dealer's ebay advert confirms it, along with a newer part number-

http://www.ebay.co.uk/itm/Fiat-Gran...Temperature-Sensor-77364869-New-/120858609342