Technical Engine warning light for the same fault in same circumstances?

[English Gent]

Hello everyone, I'm here to seek the collective wisdom of the forum..

I have a 2006 Fiat Panda 4x4 with the 1.2 petrol engine. Ordinarily I don't do a lot of mileage, so it was little more than 5 miles to the shops and back once a week, but now I have to go further, occasionally crossing the High Peaks between Manchester and Holmfirth and beyond.

On a previous return journey, the car was working hard to climb up from Holmfirth and when I started to effectively coast down hill with the car in 5th, the engine warning light came on and the water temperature gauge went to Cold. When I started to actually drive the engine along the flatter roads the temperature needle jumped up in two or three steps to the normal middle of the gauge area.

I booked the car into a local mechanic and he said the error code was for the temperature sensor which he changed (along with a service, cambelt and water pump and spotting the cause of a 'clunk' in the drive train I also mentioned - engine mount and rear differential bush had collapsed)

I had the car back after the repairs and took it a few junctions on a motorway with no problem. Then out across the moors again as far as Rotherham with no issues, until I came back towards home and the same thing with the temperature gauge going to cold and the engine warning light is on again as I started coming off the moors! The gauge started with a bit of a jump up to the middle again once I started to use the throttle.

Typical of my luck is that the nearby mechanic is on holiday for a couple of days.

I'm thinking perhaps the thermostat is sticking as it's working hard and then suddenly coasting downhill at speeds of 40 to 50mph causes the pipe where the sensor is to empty?

Any guesses? Anyone had the same thing?

 

[koalar]

Alway best to read the codes

However a quick test is discussed here along with symptoms

common problem with thermostate | FIAT Panda (Mk3)

when the weather get cold we get loads of cooling issues heaters only blowing warm P0115 error radiator fans coming on fast. gauge dropping down occationly. gauge only going up 1/4 way 90% are down to a missing rubber gasket inside the thermostat. Because the thermostat is opening and...

www.fiatforum.com

 

[RalphM]

I'm thinking perhaps the thermostat is sticking

I think your likely right.

 

[Yolanda]

Alway best to read the codes

However a quick test is discussed here along with symptoms

common problem with thermostate | FIAT Panda (Mk3)

when the weather get cold we get loads of cooling issues heaters only blowing warm P0115 error radiator fans coming on fast. gauge dropping down occationly. gauge only going up 1/4 way 90% are down to a missing rubber gasket inside the thermostat. Because the thermostat is opening and...

www.fiatforum.com

I'll put money on it, that that's the problem

 

[rmjbn1]

+1 for thermostat being the culprit, but do the checks as advised in koalar's post.

I have recently had exactly the same symptoms, long downhill (cool early morning), temp gauge abruptly dropped to zero and EML came on.

EML cleared itself, code P0115 was stored (temperature sensor) with coolant temp recorded at 60degC at time of fault.

I knew the thermostat was leaking a little (they have a rubber sealing ring which perishes over time) as the temperature gauge was sitting below half.

I suspect temperature sensor is fine, coolant dropped to 60 due to leaky stat, ECU reads this as a sensor error.

 

[bugsymike]

Hopefully the fault is as many members have experienced.
You haven't mentioned if any loss of coolant.
I have had customers cars where generally around town, etc. no issues, but when towing or pulling hard up steep hills for any length of time they were getting slight head gasket seepage, resulting in an air pocket around the temp. sensor causing erratic readings and sometimes the heater (which is the highest part of the cooling system generally) blowing cold air.
Coasting down hill temp. drops as expected, then as accelerating again air pockets may be driven to the coolant tank and car behave normally, with the only sign a slight drop in the coolant level.
Assuming 100% no coolant loss then temp thermostat issue seems most common fault to look at first.

 

[Yolanda]

I changed mine a good few months ago because the gauge wasn't reaching the middle/top hose was getting warm after half a Minuit and as you say temp gauge dropping right down when going down hill. It's been fine since.

 

[jrkitching]

I changed mine a good few months ago because the gauge wasn't reaching the middle/top hose was getting warm after half a Minuit and as you say temp gauge dropping right down when going down hill. It's been fine since.

Yes, this is a common fault on the Panda, especially those with the simple thermostat without the integral temperature sensor.

I'd strongly recommend anyone reading this to fix this (or have it fixed) as soon as you notice the temperature gauge falling from the midpoint when the engine is warm. If you leave it, the engine will overfuel as the ECU thinks it's not reached its normal operating temperature and the fuel economy will be significantly worse.

Fortunately the parts are cheap and the job is completely straightforward.

A couple of tips for anyone doing this themselves; basically the idea is to discnnect as little as possible to minimise the risk of introducing new faults.

- leave the bottom hose in place, and syphon out enough coolant to lower the level below the thermostat housing. The only hose connection you need to break is the one on the thermostat housing (but do lower the level first!)

- leave the ECU attached to its carrier and don't remove any connectors; just unbolt the carrier and swing it to one side once the battery tray is out.

 

[English Gent]

Thanks everyone..

This morning I took an IR thermometer (which I 'borrowed' from work) reading of 6c on the bottom hose. With it idling for about 5 minutes, the bottom hose was 20c and the top hose was 25c. The water lever in the filler tube was halfway between the min and max, pretty much where it was after I topped it up after the mechanic had swapped the temperature sensor and said "it'll need a cup full of water tomorrow". I drove about 10 minutes to the shops with the warning light on, then two minutes to my Dad's, with the light still on... and then when I drove away from Dad's, the light was off!

It's going into the garage on Tuesday and we'll see what happens from there!

I think I might just print off some of the tips from here for him as he's not a fiat specialist. In fact he laughed when I turned up with the Panda as he remembered me from where he used to work, when they did my hybrid LandRovers MOT. When I booked it in for next week he said it actually drives really well, and he'd had a quick look for a used one for winter!

 

[koalar]

Far simpler and better to test with your hand you don’t need to measure anything

The engine coolant warms as soon as the engine is started


The heat radiates out and warms the bottom hose and up the closed thermostat

The top hose is dry no coolant in it as it’s above the level in the radiator

There shouldn’t be anything in this hose until the thermostat has opened

If you start the car and hold the top hose you should feel nothing.

If you can feel a flow at the bottom of the hose coolant its passing the thermostat. You can tell within seconds

The thermostat housing is bolted to the engine so heat will radiate from here but takes a long time to reach near the radiator inlet

A IR thermometer will be pointing at the top of the hose, the coolant is only running in the bottom of the hose which is going to screw thing up slightly

Took me awhile to get my head around why this test works so efficiently and only the bottom of the hose gets warm.

 

[rmjbn1]

Glad to hear you've converted your mechanic to the charms of the Panda

I drove about 10 minutes to the shops with the warning light on, then two minutes to my Dad's, with the light still on... and then when I drove away from Dad's, the light was off

By 'warning light' do you mean the engine check light (aka Engine Management Light or EML)?

If so, it's normal for it to reset after detecting a temperature sensor error if the symptoms don't repeat, after a few restarts. I had this a few weeks ago.

Does your temperature gauge reach half way? Mine was below half, which indicates a leaking thermostat.

 

[English Gent]

Glad to hear you've converted your mechanic to the charms of the Panda

By 'warning light' do you mean the engine check light (aka Engine Management Light or EML)?

If so, it's normal for it to reset after detecting a temperature sensor error if the symptoms don't repeat, after a few restarts. I had this a few weeks ago.

Does your temperature gauge reach half way? Mine was below half, which indicates a leaking thermostat.

Yes, the yellow Engine shaped light. I didn't realise it would reset after a few restarts. I normally only use the car once a week for shopping . The temperature gauge was about 1/4 way up until I made it work going uphill so I could do a short coast before my estate turn off and it did got to halfway, and didn't drop much when I was coasting for maybe a minute at most.

 

[English Gent]

Far simpler and better to test with your hand you don’t need to measure anything

The engine coolant warms as soon as the engine is started


The heat radiates out and warms the bottom hose and up the closed thermostat

The top hose is dry no coolant in it as it’s above the level in the radiator

There shouldn’t be anything in this hose until the thermostat has opened

If you start the car and hold the top hose you should feel nothing.

If you can feel a flow at the bottom of the hose coolant its passing the thermostat. You can tell within seconds

The thermostat housing is bolted to the engine so heat will radiate from here but takes a long time to reach near the radiator inlet

A IR thermometer will be pointing at the top of the hose, the coolant is only running in the bottom of the hose which is going to screw thing up slightly

Took me awhile to get my head around why this test works so efficiently and only the bottom of the hose gets warm.

I did hold the pipes but didn't know what I was expecting, and I thought actual temperatures would be a good thing to report to the mechanic.

As for where the water should or shouldn't be, I wouldn't know... My mechanical knowledge topped out in the 60's, a decade before I was born.. My Landrover didn't even have an expansion tank! The radiator cap was as high as the water was kept so it's thermostat was permanently wet but just stopped the flow whilst the engine warmed up. Checking it was a few bolts and a pan of hot water, or, take off the radiator cap and look inside to see the water swirl a bit!

 

[English Gent]

My Panda has been into the garage today and he's swapped out the thermostat even though it appeared to be fine to him. The 2 week old temperature sensor was recorded as being faulty so he swapped that under warranty.

As to the pipes getting hot as I detailed above, he said there is a small bypass hose in the housing so 'getting hot' is subjective?

He doesn't think the head gasket is at fault. If it misbehaves again, it won't overheat as he's tested the fan and it still goes on and off.

His advice was to run it and see what happens? If it does the same thing again, he'd have to pull the wiring loom apart to look for a wiring fault.

What I think I'll do is purchase a fault code reader.. but which one? Anyone recommend a not too dear handheld type that does actually work with my 2006 Fiat Panda?

 

[bugsymike]

I would trust your mechanic, he has listened to all the concerns you raised and has been open minded and addressed them
Also if his Diagnostic equipment has recorded the new sensor as faulty straight away then it is probably much better than any cheap handheld device you can purchase.

 

[koalar]

.

As to the pipes getting hot as I detailed above, he said there is a small bypass hose in the housing so 'getting hot' is subjective?

Incorrect

There is no bypass valve, hole, hose in this system

There is a bleed valve built into the thermostat which is sealed shut with a small stainless steel ball as long as the system is full of coolant
???????

 

[koalar]

My Panda has been into the garage today and he's swapped out the thermostat even though it appeared to be fine to him. The 2 week old temperature sensor was recorded as being faulty so he swapped that under warranty.

Follow the link in post 2
P0115 temperature sensor error is fully explained at the end of the thread.

As to the pipes getting hot as I detailed above, he said there is a small bypass hose in the housing so 'getting hot' is subjective?

It’s not subjective if from cold it passing hot coolant past the thermostat it’s faulty. Less than a minute to test.

He doesn't think the head gasket is at fault. If it misbehaves again, it won't overheat as he's tested the fan and it still goes on and off.

Correct

His advice P0115was to run it and see what happens? If it does the same thing again, he'd have to pull the wiring loom apart to look for a wiring fault.

What ?

What I think I'll do is purchase a fault code reader.. but which one? Anyone recommend a not too dear handheld type that does actually work with my 2006 Fiat Panda?

Started a thread cheap scanner

 

[koalar]

My Panda has been into the garage today and he's swapped out the thermostat even though it appeared to be fine to him.

So if you do the test now. What the result