Cinquecento ECU Light - Peter D
Hi, my Son has cheap Cinquecento which recently required a new flexi exhaust section, no problem changed the section but on firing it up the ECU light came on and driving the car it is abruptly rev limited to about 3 K. The local agents want £65 to read the ecu not on for a 5 minute job so can anyone assist here, or does anyone know how to read or at least reset the ECU. He has searched around for the Lambda sensor connector but it appears to be hard wired. Is there a monitor point for this so I can get a scope on it. If it is the sensor and he changes it does the ECU reset itself. Thanks guys
Cinquecento ECU Light - Peter D
No help here !! Thats unusual. Peter
Cinquecento ECU Light - jud
Check to see if the wiring to a possible oxygen sensor has been damaged, during the exhast repair.
Cinquecento ECU Light - Peter D
Thanks Jud, we has done the obviuos checks thats why I also asked if there is a sensor connector as we could not find one to hook a scope into to see if the sensor produced voltage was in spec. Thanks Peter
Cinquecento ECU Light - Another John H
Reset of this ECU if it is like the Panda of K plate vintage ( poss Bosch ???? 710 or similar) - disconnect the battery for a couple of minutes.

If you do that when the engine is hot (fan just tripped in) restart without touching the accelerator, let it run until the fan has cut in and stopped again, it should be near enough to start with.
If it stalls during this learning process, disconnect the battery and repeat.

Having said that though I'd go with disturbed wiring.

Exhaust position depends on the engine - if it's the 899 pushrod engine the exhaust (and Lambda sensor) will be at the back, and not easy to see.


John H
Cinquecento ECU Light - Peter D
Thanks John, Do you know where the Lambda monitor point is and is it really wired into the harness without a connector. It is the push rod version L plate and 2 Wire sensor. Any help here appreciated. Regards Peter
Cinquecento ECU Light - Another John H
I'm not familiar with that engine with the Lambda sensor:
my current little FIAT has the FIRE engine -
but the wiring for that ( K plate Panda ) has the 'sensor' lead via a Lucar/spade connector inside a rubber boot, about 50cm of cable from the sensor.
I have inserted a thin piece of copper wire (one strand from a gash piece of multicore)inside that joint, and brought it out to a 'scope for test purposes, then removed it afterwards:
I had better than ten 0.2 to 0.8 volt crossings inside ten seconds.
That might be a bit on the slow side, but it passes the MOT, and goes well enough.

One thing which has just occured to me is the business with the earth on the 2 lead Lambda:
one lead is the switching signal.
the other is the pre-heater volts.

the earth is via the exhaust! - later installations have 3 or 4 wires:
signal earth and/or heater earth.

On mine there is an additional heavy guage multistrand (flexible) cable from a good earth point which is jubilee clipped to the body of the Lambda sensor. This has been added at some point in its chequered history.

I understand there have been problems in the past with poor earths.

Something for you to look at, if they've been a bit heavy handed with the exhaust joint sealant?


John H


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