Hi guys I have a 500 1.3 multijet that has no guts. The engine management light is up it won't rev above 3200 revs .I have bought a fiatecuscan and on using it have come up with a fault code P0641. Can anybody help me out as it seems to relate to a short circuit on some censor but which 1 I have no idea.I think it might be connected to the exhaust DPF censors but I am only guessing, if anybody could help I would be so grateful. Cheers Gary

You probably already know this........

When certain faults flash up, the ecu goes into safe mode. All engine settings go v. conservative.

Your fault code refers to a computer problem - the suggestion is to visually inspect circuit board for heat damage or poor/dry solder connections. Not sure how easy this is on a 500 - remember, this is generic code information. You either have a poor earth connection or a short somewhere in the box.

Any other members, please dive in and add to/correct the above.

What really interested me was that you have trialled the Fiatecuscan software.

When you have sorted your problem, could you feed back to us on here about how good this product is?

Good luck!

snes said:

What really interested me was that you have trialled the Fiatecuscan software.

When you have sorted your problem, could you feed back to us on here about how good this product is?

Click to expand...

:yeahthat:

...also I'd be interested to know what you are using to interface between the OBD2 connector and the USB port.

..and wishing you some more Good Luck

P0641 is a voltage low error code. What condition is your battery in? Might be worth popping it out and charging it up overnight with a decent charger, reset the code and see if the problem goes away. If it does, great. If not and its coming back I'd be inclined to swap the battery out and have a look at the alternator and connections. See if its charging correctly.

Edit: Other makes have reported this code and had to replace an ECU but my guess is that if its running, its not a dead ECU.

I don't think this problem will be anything to do with the battery or alternator.

Definition I have for P0641 is "Sensor Reference Voltage "A" Circuit/Open"

The reference voltage for most engine sensors that need one, needs to be an accurate 5 volts and is supplied to the sensor by a voltage regulator in the engine management ECU.

Unfortunately, the definition doesn't say which sensor P0641 relates to, but a previous post on here said that P0641 came up with P0340 which is "Camshaft Position Sensor Circuit Malfunction" so that could be the place to start looking.

Interesting. My data point re P0641 was from a mate with a non Fiat branded car (with Bosch electrics). He replaced the battery and it cleared fine. From what he could tell the alternator was working but the old battery wasn't holding a charge.

I'd be interested to know the final fix. If its a loose connector on a sensor that'd be great. Cheap and easy fix.

Thanks for all your surgestions I will take another look this week end.