Error Codes - P0500 & U1602 | FIAT Punto (Mk2/2b) (2024)

Here goes..

'04 Fiat Punto 1.2 8v Active.

Car is being a PITA, yesterday the engine management and steering lights came on but when I stopped and restarted they we're intermitent.

Borrowed a friends fault reader and these came up -
P0500 - Vehicle Speed Sensor A
U1602 - Manufacturer Control

What are these and how can I fix them as CHEAPLY and possible?!

I've read a few old posts/thread but didn't understand.

Dom

dombooth said:

Steering light is on and off - just done a 4 mile round trip, on way there the light was on and steering heavy, on way home the light was off and steering as normal.

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There is a loom available which provides a seperate earth which i believe connects to the speed sensor connection on the gearbox to cure this, i'm sure someone will tell me if i am mistaken.

regards

Mal

Mal126 said:

There is a loom available which provides a seperate earth which i believe connects to the speed sensor connection on the gearbox to cure this, i'm sure someone will tell me if i am mistaken.

regards

Mal

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How does it work and would it fix it? How much does it cost? And where from?

Dom

dombooth said:

How does it work and would it fix it? How much does it cost? And where from?

Dom

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Flipping eck, taking me back a bit now, mmm, cant say if will cure, have not diagnosed your car, just offering advice, think about £15 from a Fiat dealer the last time i checked, a few years ago now mind.

Mal126 said:

Flipping eck, taking me back a bit now, mmm, cant say if will cure, have not diagnosed your car, just offering advice, think about £15 from a Fiat dealer the last time i checked, a few years ago now mind.

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Yeah, £15's not too bad then tbh. Do you know anything about the other one?

Dom

if speed sensor showing a fault did speedo head work throughout all this trouble because obviously it shouldnt
might be worth checking loom to vss for water ingress and swapping vss for another one if you have one or borrow one of a mate
the other code is just generic and might be best ignored for the moment

i forgot to add the vss could cause the power steering issues too

or even a faulty alternator output could affect both these issues

s and b said:

if speed sensor showing a fault did speedo head work throughout all this trouble because obviously it shouldnt
might be worth checking loom to vss for water ingress and swapping vss for another one if you have one or borrow one of a mate
the other code is just generic and might be best ignored for the moment

i forgot to add the vss could cause the power steering issues too

or even a faulty alternator output could affect both these issues

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It reads a speed on the speedo fine.

VSS?

Ah right, if it can affect the steering I'll sort this first then. How would I test the alternator?

Dom

dombooth said:

It reads a speed on the speedo fine.

VSS?

Ah right, if it can affect the steering I'll sort this first then. How would I test the alternator?

Dom

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check connections on back and battery terminals for tightness
then with things like headlights turned on fan etc and at 2000 revs look for approx 14 volts steady on your multimeter probed onto battery terminals

s and b said:

check connections on back and battery terminals for tightness
then with things like headlights turned on fan etc and at 2000 revs look for approx 14 volts steady on your multimeter probed onto battery terminals

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On back of where? I don't know much about mechanics . If you could find a diagram or even better a photo of where it is?

Shouldn't it be 12V?

Dom

gavinh87 said:

Its ~12v before running and ~14v when running, the alternator causes this.

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Ah right, thanks. I'll do what's been recomended and report back.

Dom

U1602 - CAN Data Bus - communication error probable cause:-

Wiring, poor connection.

As for the speedo thing - it needs a modified loom - only fiat can do this
Should be free IIRC, but times change tho - could be a lil penny now

Ziggy

Mal126 is correct in what he says (will bring steering light on as well as stated) about the loom although it's actually £32.

U1602 is manufacturer specific and is 'keycode minicrypt, in other words key not read correctly so we can disregard this & concentrate on p0500.

If your car has ABS the speed signal comes from here & not VSS.

Ziggy122 said:

U1602 - CAN Data Bus - communication error probable cause:-

Wiring, poor connection.

As for the speedo thing - it needs a modified loom - only fiat can do this
Should be free IIRC, but times change tho - could be a lil penny now

Ziggy

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T14086 said:

Mal126 is correct in what he says (will bring steering light on as well as stated) about the loom although it's actually £32.

U1602 is manufacturer specific and is 'keycode minicrypt, in other words key not read correctly so we can disregard this & concentrate on p0500.

If your car has ABS the speed signal comes from here & not VSS.

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Right, so I need to get the loom from Fiat? Do they fit it for the £32 or do I?

Also, I don't know if it has ABS or not, so where does the speed signal come from in both cases (ABS and VSS)? Diagrams/pics would be appreciated.

Cheers,
Dom

dombooth said:

Right, so I need to get the loom from Fiat? Do they fit it for the £32 or do I?

Also, I don't know if it has ABS or not, so where does the speed signal come from in both cases (ABS and VSS)? Diagrams/pics would be appreciated.

Cheers,
Dom

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The above still applies but...

The light haven't come on at all today so I'm hoping it had it's strop and now it's behaving.

Dom