Hello everyone!

I just joined this forum as I have some problems with my Fiat Punto 1.2 8V, 2003 year, facelift model.

Bought this car with 80 000km, and now it has 240 000km, its an amazing car, cheap to maintain and didn't used alot of fuel, my average was 5.2 - 5.8 liters per 100km! I drived it to work and back home, it was around 60km in one direction on an open road. So the car didn't see alot of city driving.

Anyways what happened to me now is a bit strange. So this year it was cold outside, around -5C, and I got yellow engine warning light suggesting something is wrong with the engine, and engine temperature gouge would stop working. It would show like engine is cold. This happened while I was driving.

Next morning I went and washed my car with a miniwash, with warm water, and when I turned on the car, light was gone. Then same thing happened few days after that, it was cold outside around -10C, and yellow engine light would start. Car would run normally, but yellow engine light was there. Then two days after that again I washed my car and light was off

I thought it was just some sensor was freezing so not a big deal.

But now I have a problem with high fuel consumption. When I'm accelerating it says its using 25l/100km on the dashboard. While driving normally its around 10l/100km. And thats 90km/h at 2900RPM. It would usually use around 5.2 - 5.8l / 100km at that speed / RPM!

The car is amazing, everyone is teasing me how I drive a bad car, but I love it, its easy to maintain, has cheap parts, low consumption, would really love to solve this issue.

So what do you guys think what could be the problem here?
Lambda sensor? Temperature sensor? Fuel pump?

I just changed motor oil, oil filter and air filter my self. Then drove to a guy to change spark plugs as I could not get them. And he told me spark plugs were black, and it means that they are getting too much fuel. So something is off there! Just don't know where to look for the problem really. Anyone had similar issue?

And a few questions if someone has time to answere:
1. Whats Punto 2b? MK2 is 2nd model I get that. Is 1b pre facelift and 2b is model that got the facelift?
2. What is the best diagnostic tool to buy? That I could connect to my car and read errors on Android smartphone? Would really love to have it so I can check for problems on my own.

Thanks everyone, I decided to get my hands dirty and show some love to my bad boy! Until now I just changed oil / filters regularly. And changed clutch, and back breaks and back "shock absorbers"!

Now I wanna take this car apart and fix and improve everything I can.

it sounds classic coolant temperature sensor
any ebay type code reader that can read live data should be able to show you if i am correct

eg https://www.ebay.co.uk/itm/D900-Car...h=item1eefa0ee7b:g:qAYAAOSw0~pb~Ng~:rk:6:pf:0

If the thermostat is not working,always open and the result is cold engine, as it should then the engines uses too much fuel .

BILL33 said:

If the thermostat is not working,always open and the result is cold engine, as it should then the engines uses too much fuel .

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And why..pray tell ..would the yellow light be lit ?

varesecrazy said:

And why..pray tell ..would the yellow light be lit ?

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and that's why they suggested a fault code reader so the car can tell you whats wrong. Yellow light is Engine management warning light, usually comes on when one of the sensors detects an issue. If the coolant temperature sensor is knacked and engine is running cold (hence high fuel use) then the light comes on to tell you something is wrong.
Pre facelift Punto is Mk2A...facelifted is Mk2B

I am suprised you would get a warning..

Thats all

Yes you can plug into OBD Port and get a reading of what temps the ECU is 'seeing'

But cold is 'just cold'. Where as Hot is seen as OVER TEMP. ..you get the red temp light.

Thanks everyone for your replies guys! It means alot!

The yellow engine light would turn on, and off periodically!
It would turn on in the middle of me driving the car, and then turned off when I would wash the car with warm water

At this moment, yellow engine light is off, its not showing any problems on the dashboard, but the fuel consumption is huge. From an average of 5.5l it went to 10-12l per 100 km! And also now the temperature gauge on the the dashboard is showing me real temperature, I can see it rise up when engine is working and I'm driving the car. But fuel consumption is huge.

I also thought its a problem with temeprature or lambda sensor. But didn't knew where its located. Will check it all now and start replacing sensors, and also order code reader to see what is ECU seeing!

lesavage said:

Thanks everyone for your replies guys! It means alot!

The yellow engine light would turn on, and off periodically!
It would turn on in the middle of me driving the car, and then turned off when I would wash the car with warm water

At this moment, yellow engine light is off, its not showing any problems on the dashboard, but the fuel consumption is huge. From an average of 5.5l it went to 10-12l per 100 km! And also now the temperature gauge on the the dashboard is showing me real temperature, I can see it rise up when engine is working and I'm driving the car. But fuel consumption is huge.

I also thought its a problem with temeprature or lambda sensor. But didn't knew where its located. Will check it all now and start replacing sensors, and also order code reader to see what is ECU seeing!

Click to expand...

Read the OBD codes 1st.

No point replacing perfectly serviceable parts..

And whilst you are waiting.. take out the spark plugs..

Line them.up in the order they were installed compare the colours around the electrode

Showing us those colours could be VERY helpful in a 'web diagnosis'

varesecrazy said:

Read the OBD codes 1st.

No point replacing perfectly serviceable parts..

And whilst you are waiting.. take out the spark plugs..

Line them.up in the order they were installed compare the colours around the electrode

Showing us those colours could be VERY helpful in a 'web diagnosis'

Click to expand...

Thanks for reply

I already changed spark plugs with the new ones. A guy I know in town did it, as I could not do it my self, they were really deep behind engine

Spark plugs were all the same color, but were really black, and the guy told me its cause they get too much fuel. He didn't had time to do a "full diagnostic" as he was in the middle of the work when I stopped by, he said I can come next week so he can inspect everything, but it would cost me a ton haha And I would like to do it anyways to learn more about the car.

I don't have code reader yet so nothing I can do there until I order it.

Can anyone suggest a good code reader I could order off ebay or some other web shop? I see there is alot of them, but there must be some best buy readers out there

I think I'm gonna change termostat, temeprature sensor and coolant tomorrow and see if it helps.
Now I'm going to garage to check all the contacts and clean them, could be I'm loosing contact somewhere, its strange that light would come on, then disappear when I would wash the car with water, could really be bad contact somewhere. Will let you know what happened when I check the contacts now!

Ok.

Plug colour NOW was what I meant.

Odb is a standard... so all readers should do basic engine codes.

If you like Italian cars get Multiecuscan

If you just want to get basic engine codes

Prices start at £8

Personally I have a VS600

type that into ebay.

Whatever method you use to get a code.. type that code into the forum SEARCH then you will find relevant threads.. often with solutions.

Cant you just hold the water pipe coming out the top engine on the battery side going to the top of radiator and see if it thermostat is stuck open. The radiator at that corner will start getting warm straight away if so.
If thermostat is working radiator wont get hot until it opens after running engine for a while.


Also your lambda sensor could be shot, try swapping them over.you have one before and after cat converter.

OBD will tell you if its going into closed loop or not and if your lambda is busted. you can also see what temp the ecu is reading.

But could also be my old friend the idle valve! faulty in injector, vacuum leak etc

Not sure about water temp making your fuel consumption rocket thou as i would have thought it would get hot enough after a while but maybe not in this weather, It might be more like too much air in the mixture or fuel. Ecu needs to balance these 2 out via lambda reading.

Even if its not in closed loop if fuel consumption really high then it sounds like a issue with air or fuel as it should not be much higher than closed loop. I think the ecu would still control the fuel and air based on revs rather than lambda sensor.

Ok guys, I just came from the garage and I'm even more confused now!

Much thanks to puntoFix for his suggestions, I will read your post one more time and go check everything.

So it seems I fixed my problem, for now at least, but I don't really know how

I went to the garage with intention to remove all the wires and check if they are all connected right, check for lose connections or if any of the wires disconnected.
I removed air filter assembly and battery and check all the wires.

First thing I found is that I had a broken wire somewhere on the transmission, here: !not allowed to post URL's! , and the white wire was disconnected: !not allowed to post URL's! I figured out this was reverse gear switch, and noticed that wire was soldered as the plastics around the wire was burned, guess previous owner did that. I installed battery back and put the car in rear gear and the back white indication light was not lighting. So I soldered that wire back and the reverse gear light now turns on. I know its not a good solution, its sunday today, so I will go into a car store tomorrow and try to find new connector and change the broken connector.

Now the interesting part starts, I located the temperature sensor and unplugged it, and found out there was some liquid in it, on connections, was it water or antifreeze I don't know. I used cotton swabs, for ear cleaning, and cleaned all the liquid out of there, cleaner everything around it and put the plug back. This is how it looked clean: !not allowed to post URL's! and !not allowed to post URL's! . The last photo shows the female one, that one had some liquid inside that I cleaned. And thats it, thats what I did guys. I also disassembled air filter assembly when it was out already and thoroughly cleaned it, but thats it. I just cleaned temperature sensor plug.

Then I put everything back at its place and started the engine, it was all good, but yellow engine light was now on, it was off before I started messing with the car. So OK I think its on now cause I disconnected the temperature sensor. Then I went home, driving around 10km, and noticed my fuel consumption is back to normal again. OK thats good, it was around 5.5L /100KM thats really good. So problem solved right. Yellow engine light in the photo: !not allowed to post URL's!

But now I have another problem, yellow engine light is on, hmm... last two times when I had that yellow engine light on, I washed the car and it would disappear. I decided to go and wash the car with high pressure washing machine. So I got there and noticed my average fuel consumption is now 4.9L/100KM. I washed the car for 1 euro, thats like 120s of washing, turned the car on, and yellow engine light disappeared Car was good as new. I looked under the hood, maybe water was leaking over some wires / sensors so it made "better" connection, nothing, everything was dry, and water didn't touch temperature sensor. EDIT: Maybe water did leak on the ECU connections, will check that now! Didn't disconnected ECU as it looked complicated, will check now how its done. Maybe I have some loose connections there!

Then I went on and drive another 15km around the town to check fuel consumption, this is what I get: !not allowed to post URL's! and !not allowed to post URL's! Made 15km, and average fuel consumption was 5.0L / 100KM! That's about how it used to be. On average my fuel consumption was 5.2 - 5.8L / 100KM! And I drive on an open road mostly, 90km/h is top speed I drive at. I change to higher gear at 3000RPM or a little bit higher, back to lower gear before 2000RPM, and I'm driving like that for years. Did the same with this test run.

Now I'm confused as I never was, how can washing car with high pressure washer clear engine warning? It didn't happened once, this is 3rd time this happened.
When I turned the car on and saw the engine warning disappeared, I almost started hitting my head against the steering wheel!
Temperature outside now is around 10 Celsius, nowhere near freezing. My first thought was, sensor froze, when I washed the car with hot water it unfroze, but thats not the case.

First problems started with temperature sensor, in the middle of driving, temperature gauge would drop to 0, yellow engine light would turn on, and the fan under the hood started working like crazy, so yeah that was temperature sensor problem for sure. That happened two times, but it stopped. And yellow engine light was off, I only had problems with high fuel consumption. I guess I had issues with temperature sensor connection.

Anyways I'm just confused really, will find the best code reader i can afford now and order it, and will show some love to this bad boy I own. Will fix something each week on this little car. First thing is coolant change, will do that this week. I'm happy I found this community, as there are some amazing guides, and people here ready to help as you are helping me!

I can't upload any photos, as I just joined, will upload them when I become more trusted member here. Or if administrator can enable me to link the photos, that would be great!

puntoFix said:

Cant you just hold the water pipe coming out the top engine on the battery side going to the top of radiator and see if it thermostat is stuck open. The radiator at that corner will start getting warm straight away if so.
If thermostat is working radiator wont get hot until it opens after running engine for a while.

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I can see you are a man of vast experience, will go and do that right now!
Will check what you said there, and reset fuel counters and drive a car some more, can't believe just cleaning the temperature sensor connection solved issues I had.

I have the drop to zero issue and then engine management light turns on. I do not have the bad consumption issue though. I have changed the sensors with no effect. The engine light will go off if the drop to zero does not reoccur for 3 or 4 engine restarts. My engine management light turns on consistently in cold weather below 12C and after at least 45 minutes of drive with little engine load (below 50mph and on a downhill). Managed to drop the temperature to 8C by partially covering the front of the radiator (40% coverage). So the problem may just be a faulty thermostat that causes the ECU to think there is something wrong with the temperature sensor drops the gauge to zero and then throws an error.

The trip computer may be lying so you need to confirm consumption using the hard way. My trip computer always lies by at least 3mpg on a long run taking the average. Up to 10% worse fuel consumption in extreme cold weather is to be expected.

I just made another run with my Punto, 25km and fuel consumption was 5.1L/100KM!

Yeah I know it lies to me, its not 100% accurate, but its a good reference point. It was around 14L/100km, before I cleaned temperature sensor contacts. Now its back to 5L/100km so its a good reference.

I had the same issue as you dumbledore. While driving, yellow engine light would turn on, and temperature gauge would drop to zero, and fan on the radiator would spin at 100%! My logic was that ECU lost connection to temperature sensor, so it turns fan to 100% to save the engine from over heating! I thought that happened cause sensor was frozen, but it turned out it was not.

So I feel my problem is fixed now, only thing I can't figure out is why would yellow engine light disappear after washing a car with hot water Maybe its just coincidence and would turn the light off anyways after few restarts, but it happened 3 times in a row so

dumbledore did you try checking if ECU reads right temepratures from temeprature sensor? Maybe you replaced temperature sensor but your wires are disconected somewhere?

How would you check for that? Turn on the car, disconnect temperature sensor and measure voltage at connector? How high voltage should you get? 5V?

Are there any guides on voltages that should go through sensors?

lesavage said:

Maybe you replaced temperature sensor but your wires are disconected somewhere?

How would you check for that? Turn on the car, disconnect temperature sensor and measure voltage at connector? How high voltage should you get? 5V?

Are there any guides on voltages that should go through sensors?

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The wire maybe broken but highly unlikely. I cleaned the contacts several times, replaced the sensor and also cleaned the contacts at the ECU side. The fact that is very consistent over 45 minutes of drive and low engine stress makes a broken cable very unlikely. A broken cable will give zero readings erratically.
The sensors is just a variable resistor that goes low when hot and high resistance when cold. The ecu will need to just measure the resistance and then convert it to temperature using some programmed maps specific to the sensor. One day I'll read the code to see if I get any more clues of what is going on. I've got a cheap odb2 reader will that be OK on a mk2B?

I think if you disconnect the temp sensor the fan comes on as a fail safe.
So that would make sense with what you have seen.

Scary on the fuel consumption based on that thou

I dont have a fuel usage meter on my 2000 8v. Can you look at the revs on cold start up and watch them drop after a while would give you a reference next time what reading they are.
should drop when in closed loop.

But you can also smell it running rich on start up and then leans up when in closed loop.

Mine was running rich all the time and I had a bad pre cat Lambda sensor and a Fubar idle valve.
My consumption gauge was the amount of money I was spending on fuel and a constant rich fuel stinking exhaust;-)

OBD will tell you all sorts of good stuff I got a cheap bluetooth 6£ off ebay and use my phone to see sensor info.

Glad you fixed it thou.

dumbledore said:

The wire maybe broken but highly unlikely. I cleaned the contacts several times, replaced the sensor and also cleaned the contacts at the ECU side. The fact that is very consistent over 45 minutes of drive and low engine stress makes a broken cable very unlikely. A broken cable will give zero readings erratically.
The sensors is just a variable resistor that goes low when hot and high resistance when cold. The ecu will need to just measure the resistance and then convert it to temperature using some programmed maps specific to the sensor. One day I'll read the code to see if I get any more clues of what is going on. I've got a cheap odb2 reader will that be OK on a mk2B?

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Can you give me the model of ODB2 reader you bought?
Im looking for a reader too at this very moment

Also for more experienced guys, I see you can read codes with reader, can you also reset error codes with a cheap ODB2 readers?

puntoFix said:

I think if you disconnect the temp sensor the fan comes on as a fail safe.
So that would make sense with what you have seen.

Scary on the fuel consumption based on that thou

I dont have a fuel usage meter on my 2000 8v. Can you look at the revs on cold start up and watch them drop after a while would give you a reference next time what reading they are.
should drop when in closed loop.

But you can also smell it running rich on start up and then leans up when in closed loop.

Mine was running rich all the time and I had a bad pre cat Lambda sensor and a Fubar idle valve.
My consumption gauge was the amount of money I was spending on fuel and a constant rich fuel stinking exhaust;-)

OBD will tell you all sorts of good stuff I got a cheap bluetooth 6£ off ebay and use my phone to see sensor info.

Glad you fixed it thou.

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I can't thank you enough, you gave me some really valuable info!

Can you please explain closed loop a little bit better, as I don't understand what you are talking about
Closed loop is when there is no coolant circulation? So thermostat is not working when you have closed loop?

I think my revs on cold start are higher then later. So I start the car, revs go high, then slowly get under 1000 RPM. They are higher at start, then get lower. Is this good or bad?

I tried starting the car and touching the water pipe coming out the top engine on the battery side, it did get warm, but not hot. So it was not warm but mild like not hot really. Car was running for 2 minutes and water pipe was warm but not hot. Should it be cold, like really cold?

For now as I tested it car works much "calmly" really and fuel consumption is good again. Will order OBD2 reader tomorrow, will get it in 2 days.

Im thinking now... maybe disconnecting battery for 2-3h helped me? Maybe some codes or ECU was reset so its back to normal consumption