My version of Punto is a MK2 2001, oil light suddenly became permanently visible last week, in attempt to clear the fault i`v renewed oil & filter which i`v done many times before on this car, further investigation showed the pressure switch to be at fault which i`v now renewed although red oil light remains on all the time, i can check that the switch is working correctly as i have electronic knowledge, i`m now wondering if a code reader might show the problem once existed and hence allowing me to reset the condition although much time spent searching FF and googling has not given me any clues so i`m now asking for and opinion here please, any thoughts? Many thanks.

Check that the switch wiring is not broken from rubbing on something or some other cause.
Check that you have supply at the plug, 5 Volts probably.
Open the valve cover and see if the spray bar is delivering oil to the top.
The sump pick up pipes are easily broken on these especially if the sump has been replaced without dropping the exhaust out of the way.
Not sure about the oil pressure warning but if the temp switch is disconnected with the ign on the car will throw a red warning lamp and a yellow eml light which will stay on for the next three cycles until the ecu is sure it's gone away.

Thanks Brendan
Cable to pressure switch is in tact and has 12volts at engine end. Switch is being opened as soon as engine starts up sensing the presence of oil pressure so no problem their i feel. This car been i my possession since it was three years old at 23k miles, unlikely sump has been off before that time and certainly hasn`t been removed in last 14 years. This all just leaving my final thought which is does the computer system require a reset via a code reader? Thanks all.

Fiat MES is the business for scanning and clearing. The engine module is free so all you need is a laptop and an interface, I use an ELM327 wired unit although there are other options.
http://www.multiecuscan.net/
If you register, pay 50 euro, you have access to SRS and power steering. Depending on the interface firmware and terminations you may have comms issues with the pay modules. Desoldering a resistor on the CAN pins fixed it for me.
http://forum.multiecuscan.net/viewtopic.php?f=5&t=1493
I have never seen a car hold on to an oil pressure warning light if the switch is working and the pressure is up.

If u leave the switch disvonnected - the light wont come on
If it is - then it instantly says a wiring fault

Switchs are cheap and easy todo - if u dowt it been at fault

Failing that it needs an actual oil pressure guage fittin and test...

Ziggy

Trader Tony said:

Thanks Brendan
Cable to pressure switch is in tact and has 12volts at engine end. Switch is being opened as soon as engine starts up sensing the presence of oil pressure so no problem their i feel. This car been i my possession since it was three years old at 23k miles, unlikely sump has been off before that time and certainly hasn`t been removed in last 14 years. This all just leaving my final thought which is does the computer system require a reset via a code reader? Thanks all.

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Hi Tony,
Sounds like you may have a computer or a wiring issue. What engine do you have?
Multiecuscan www.multiecuscan.net will allow you to see what the ECU thinks the oil pressure switch is saying. On most newer cars will also let you turn the light on and off regardless of pressure but I'm not sure about yours. Well worth investing in a copy and a ELM 327 interface. A <£20 like
https://www.ebay.co.uk/itm/323081904143?
Will work out of the box but the very cheap ones may have a design flaw of a 120 ohm resistor connected between pins 6 and 14 that needs to be removed.


Robert G8RPI.

is engine knocking when light comes on?

Deja Vue i have same problem. car was ok when last used 3 days ago,switched on this morning and oil light on.Recently changed oil and filter so full with oil. Let it run for 3 mins no knocking sounds. Can someone tell me where the switch is located so i can check it out? Thanks

texx said:

Deja Vue i have same problem. car was ok when last used 3 days ago,switched on this morning and oil light on.Recently changed oil and filter so full with oil. Let it run for 3 mins no knocking sounds. Can someone tell me where the switch is located so i can check it out? Thanks

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Literally on the same housing as the oil filter
As the filter screws in passenger towards driver side
On the other side is a big (22mm??) Hex nit with a plastic body
Single pin connection

The oil sensor is just a switch - no oil pressure or low enough to allow the pretensioned ball and spring to touch the bottom and close the circuit illuminating the light
Once the threshold is passed the oil pushes the ball up off its seat - making it open circuit = light goes out

Ziggy

Thanks Ziggy,as switch is very cheap i have a new switch arriving in the morning, that will at least eliminate the switch. Do you need to drain oil before taking out?

texx said:

Thanks Ziggy,as switch is very cheap i have a new switch arriving in the morning, that will at least eliminate the switch. Do you need to drain oil before taking out?

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Hi Texx

Having just renewed my pressure switch i can tell you that as you remove the switch oil will drip so put your finger over the hole and have the new switch and cloth handy, my spanner size is a 21mm open ended

Thanks Tony but i might not need to do it after all. This afternoon i switched on engine and red oil light was still on, so i connected the Multiecuscan and it came up with a fault code for Key lock P400 or P600 i think,anyhow as soon as i hit clear error the light went out! Very odd but then puntos do seem to suffer from electrical "gliches" Ive just taken car for a 15 mile run and all ok.

Thanks G8RPI Robert
Really appreciate your thoughts. Engine is 1200 16 valve 51 plate. With ignition on and cable disconnected at the switch end I have 12 volts at the switch end of cable and light is still red, with cable connected as soon as engine fires up the switch is opened suggesting sufficient pressure from oil although the light stays on. This leads me to suspect a fault with the cpu that manages the warning lights display or maybe a code reset although i`m not finding any info that suggests this oil light is managed by CPU codes. I`l investigate your link. Strange that i appear to have 2 faults that have both occurred at the same time.

Thanks Texx that was quick reply. Oh so very interesting that the reader gave you a code to reset the light, where did you get it and what price please?

Trader Tony said:

Thanks Texx that was quick reply. Oh so very interesting that the reader gave you a code to reset the light, where did you get it and what price please?

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Hi,
Sorry to jump in. Texx is using the same diagnostic software s I suggested. An interface and registration fee is about £50-60. It's worth every penny, but if you are near Cambridge I can put my set up on it for ou.

Robert G8RPI.

Trader Tony said:

Thanks Texx that was quick reply. Oh so very interesting that the reader gave you a code to reset the light, where did you get it and what price please?

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You can Get MES from here..http://www.multiecuscan.net/
Leads to connect it can be found on Ebay..https://www.ebay.co.uk/itm/Fiat-Alf...143922?hash=item1ca1d485b2:g:89MAAOSwmUdUVQ4C

Only other thing you need is a Laptop.
Multiscan is Free, but some features are locked unless you have the paying version.
Free version will read and reset codes

Thanks Robert G8RPI for your generous offer of a visit to cambridge which i`m sure would be great although that's 150 miles or so each way. I dont have a laptop merely a large PC so I`m wondering would a code reader such as this one do the same job:-

https://www.ebay.co.uk/itm/UNIVERSA...e=STRK:MEBIDX:IT&_trksid=p2055119.m1438.l2649

Thanks, Tony

Trader Tony said:

Thanks Robert G8RPI for your generous offer of a visit to cambridge which i`m sure would be great although that's 150 miles or so each way. I dont have a laptop merely a large PC so I`m wondering would a code reader such as this one do the same job:-

https://www.ebay.co.uk/itm/UNIVERSAL-ALL-Car-fault-reader-code-scanner-OBD-2-diagnostic-tool-CAN-RESET-TOOL/132405799776?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2055119.m1438.l2649

Thanks, Tony

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Hi Tony,
That reader will not do a fraction of what Multiecuscan can do. In particular it will not allow you to look at the status of the the oil pressure input or turn the light on and off. MES will do both of these. You don't need a fncy laptop anything running windpws XP or newer will work. I've even used an old Sony VAIO that came from freecycle (for free). There are lots of suitable ones on ebay too.

Robert G8RPI.

.......and tecnically you don't need a laptop either. You can download MES to the PC and bring it out to the car with an extension lead.

Brendan W said:

.......and tecnically you don't need a laptop either. You can download MES to the PC and bring it out to the car with an extension lead.

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Very true, although I personally find a laptop more portable than my Desktop..
But yeah basically all you need is a bare bones PC..ie Tower, monitor, Keyboard and mouse