Technical 2005 with P0115 error

[koalar]

Search the forum and web seem others have had the same fault but the threads go dead without answer.

Temperature gauge goes to zero and the engine check light comes on.

First its very intermittent. I can do several 100 miles of mixed driving with no problems


Second its not the coolant sensor. New one has the same intermittent fault. Two identical would be unlikely.

The coolant has been drained and bleed. It was nice and clear no scum or oil.

Fails more often going up hill but might be a coincident.

Sometimes temperature gauge is only reading 1/4 but after 5 minutes rest when you switch the ignition back on it read correct 1/2


Gauge read zero switched the engine off and back on and it started to work.

Failed last night after 5 hours of driving in a 10 hour period. The ignition off and back on again trick didn't work this time but did fix itself a few hours latter without touching anything.

 

[DaveMcT]

It sounds like a sensor fault. There used to be two. One for the ECU and another for the gauge. Check the manual.

However make 100% sure you don't still have air bubbles in the system. Squeeze the top hose and bleed air with engine NOT running. Also consider bleeding with LH side of car higher than RHS so bubbles can rise towards the bleed screw.

 

[Thefox]

You need a diagnostic computer connected and look at the live parameters with engine running and fault present. See if the coolant temp is there when fault present. Make sure the connection to sensor is ok and the pins aren't wide causing poor connection.
Also check air temp sensor in throttle body. Quite a common fault on Grande punto. Check the live readings to see what temp is measured.

 

[irc]

Might sound improbable but check the engine and chassis earths, just to rule them out as it is cheap to check them.

When it is playing up, use a booster cable (jump lead) to connect battery earth to engine block. If gauge then reads correctly, clean or replace your earth leads.

I chased a similar problem for quite a while before I found a corroded chassis earth lead.

 

[koalar]

Thanks for the replies.

Unfortunately I don't have access to any live data


Very unlikely to have a second sensor that's identical to the first.


I fairly confident there is only one sensor for both the ECU and gauge.


A copy of the wiring diagram would be helpful


Should have checked the +5 volts last night while it was failing.


Did check the bleed screws while it was hot and failing no air came out off the one by the heater matrix or top of the radiator. Coolant level remains constant.


I will check the earth leads when its light outside..


Shame some of the older thread haven't been updated. See a few around 10 years ago with the same problem and no conclusion. Seems to happen on the Punto as well but didn't see any on the 500?

 

[DaveMcT]

In the days of the Punto Mk2 the FIRE engine had two temperature sensors. Fiat don't change very much so the Panda could well be the same.

http://www.multiecuscan.net will allow you to read everything you need and more for very little money.

 

[koalar]

Found the wiring

Only two wires from the ECU to the sensor and four to and from the body computer and dash

Can't post a URL yet but below should get you there

fiatforum(dot)com/panda/266137-panda-fan-not-cutting


Have to see if I can sort out a radio code so I can disconnect the battery and check the ECU end.

 

[varesecrazy]

https://www.fiatforum.com/panda/266137-panda-fan-not-cutting.html

radio code = body ecu should recognise original radio, so not normally an issue,
Charlie - Oxford

 

[koalar]

Cheers everyone. I will wait until my cable arrives before going any further.

Hope I have bought the right one. KKL switched. Think it will read the sensors but not the dash If I have read the compatibility chart correctly.

Downloaded Multiecuscan gives a list of ECU's how do I know which one.


Also cable comes with a driver disc but my tablet has no CD drive. Guess the driver will be posted on the internet somewhere.

 

[varesecrazy]

drivers are usually on the web. yes.

connect to cars socket, then SCAN for devices - it'll only list what it connects to..

Charlie

 

[koalar]

Cable arrived. bought a switched one so I can fix my airbag latter. All working fine

Here's the error


Error details:
Fault status: signal not valid
Engine temperature: 60°C
Engine speed: 1500 rpm
Intake pressure: 192 mBar
Engine status: running
throttle angle: 0 deg
Spark advance: 17.0 deg


Start the engine and logged the intake and coolant temperatures.


Both rise normally and coolant stops just over 90 and intake 18.


Both the top and bottom hoses from the radiator are warming up at the same time.


My guess is the thermostat has stuck open and as the outside temperature has dropped the coolant temperature has fallen below a set threshold of 60 and triggered an error. Would fit with the error appearing as the weathers got colder and while on traffic free journeys.


Gauge has mainly been low since I got the car in August. Still getting over 60 mpg though.



Guess this is what's involved I know its a Punto but looks very similar engine to mine.

 

[koalar]

drivers are usually on the web. yes.

connect to cars socket, then SCAN for devices - it'll only list what it connects to..

Charlie

Cheers Scan worked a treat

 

[varesecrazy]

Both the top and bottom hoses from the radiator are warming up at the same time.


My guess is the thermostat has stuck open and as the outside temperature has dropped the coolant temperature has fallen below a set threshold of 60 and triggered an error. Would fit with the error appearing as the weathers got colder and while on traffic free journeys.

Gauge has mainly been low since I got the car in August. Still getting over 60 mpg though.

Guess this is what's involved https://www.youtube.com/watch?v=k-OjnrIgS_A I know its a Punto but looks very similar engine to mine.

hi,

TOP TIP,
IF you want to change the thermostat..

remove vehicle battery for access , keep coolant system sealed = CAP ON

swap the thermostat and Gasket, ( you'll need a replacement hose clip)

then remove radiator cap and top up to MAX level, should need less than 400ml

you should be good to go ( once you've refitted the battery)

Charlie

 

[koalar]

Changed the thermostat today.

Yes the old one is permanently open. Its missing its rubber sealing ring. Old one is nowhere to be seen. Spent more time trying to find it than doing the job.


Bought a thermostat from a local motor factors £10. Branded "first line". Very poor casting when compared to the original. First if you look down the original the internal projections are streamlined whereas the copy are flat. Where the hose connects is also a poorer design than the original and the gasket is paper no big deal and fitted any rate

Didn't bother taking the battery tray off. There enough room to easy remove the thermostat as long as you have the correct length extension bar.


It was difficult to see if the matting face was clean due to the overhanging coils. Took a picture to confirm it was clean.


Connected to the hose first with a new clip and then reassembled and tightened to 10 nm

On start up the upper/top hose now remains cold. Been for a drive and the temperature gauge now rises to the centre and stays there.


So far so good. Was a couple of months between errors in summer so fingers crossed it finally fixed.


Conclusion. P0115 probably has several causes. In my case P0115 plus low temperature gauge plus top hose instantly getting hot equals thermostat