When I hit 70mph on the motorway, the EOBD, General Failure & Start/Stop Deactivation lights come on. After a few seconds, the EOBD then goes out. (But the other two lights stay on)

The car doesn't go into limp mode and continues to drive fine. If I turn the engine off & on again, the lights are cleared.

I asked my local Fiat dealer, but they want £120 to diagnose the issue and give me a quote to fix the issue!

Is this my only option?

Thanks

I'm no expert, but I'd ask an independent garage if they have heard of this.
The Start/Stop thing scares the hell out of me, because every few months when I'm at low revs (still in gear, between 5/15mph) SS will suddenly decide to activate and simulates/causes a stall of sorts. It gives the 'S/S Disconnected' message and the clutch/accelerator cease functioning, and the only way to fix it is to turn the car off and on again. It happened to me last week whilst slowly crawling into Southampton.

I've heard of things like you describe when the car has a faulty battery. For reference I've got a 3 half yo 500S TA (85).

Hello and welcome.

Sorry it's in such sad circumstances.

Yours is a commonly reported fault, but having it triggered on reaching 70mph is a new one on me. A failing battery is frequently to blame; if the one in your car is more than 2-3yrs old, replacement is probably the best way to confirm this as even batteries which perform well under a load test can still be weak enough to cause this issue. It's essential to replace it with a S/S battery of the correct specification (about £100 or so if sourced competitively).

Checking the integrity of the rear hatch wiring should also be an early test on any 500 with a suspected electrical problem as this frequently fails, causing random electrical faults.

nmysbh said:

I asked my local Fiat dealer, but they want £120 to diagnose the issue and give me a quote to fix the issue!

Is this my only option?

Click to expand...

If you have a windows laptop, you can do your own diagnostics with a licenced copy of Multiecuscan + a few cables for about half that.

DBunX said:

I'm no expert, but I'd ask an independent garage if they have heard of this.
The Start/Stop thing scares the hell out of me, because every few months when I'm at low revs (still in gear, between 5/15mph) SS will suddenly decide to activate and simulates/causes a stall of sorts. It gives the 'S/S Disconnected' message and the clutch/accelerator cease functioning, and the only way to fix it is to turn the car off and on again. It happened to me last week whilst slowly crawling into Southampton.

I've heard of things like you describe when the car has a faulty battery. For reference I've got a 3 half yo 500S TA (85).

Click to expand...

Try turning off the SS every time you drive the car for a few weeks and see if it does the same thing, is it the SS or is it simply stalling? When did your car have a new battery, its not the original is it?
I've gathered(but I'm no expert) that the brake/clutch/gear selector switches can also cause issue with the SS.

nmysbh said:

When I hit 70mph on the motorway, the EOBD, General Failure & Start/Stop Deactivation lights come on. After a few seconds, the EOBD then goes out. (But the other two lights stay on)

The car doesn't go into limp mode and continues to drive fine. If I turn the engine off & on again, the lights are cleared.

I asked my local Fiat dealer, but they want £120 to diagnose the issue and give me a quote to fix the issue!

Is this my only option?

Thanks

Click to expand...

Not your only option, ask a few mobile service/diagnostic companies if they specifically have the Fiat system software rather than a generic system for a price and tell them whats going on, rather strange it is though.

One of the specialists would probably read the fault and give you an idea for nothing!

I turn the SS off as a matter of course, its great for Fiat's emission readings, but crap for turbo engines!
I have never used it on the TwinAir. When we first had the 1.2, the SS would occasionally get its nickers in a twist at the position of the clutch pedal and I have seen new 1.2 500 hire cars do the same!
So it's turned off and I have never had an issue since