Technical ECU Rolling code problem ? My beautiful Panda 1000 won't start.

[Nono21]

Hello everyone,
I’m new to this forum. My name is Arnaud, and I’ve been working on an old 1993 Fiat Panda 1000 since last year.

I’ve had quite a few issues with the car, but I think I’ve managed to fix about 90% of them.

In September 2025, the original ECU (IAW 6F.SH) failed. I temporarily replaced it with a 6F.SB ECU from a Fiat Punto 1.1 Fire, and the car actually ran quite well with it.

However, the 6F.SB ECU is calibrated for a larger engine, so it injects too much fuel for my 1.0 engine.

Because of that, I sent my original ECU (6F.SH) for repair. I sent it back because the car never started with it after a first reparation.

The technician who worked on it told me that the ECU itself is now fine, but that there is a “rolling code” issue preventing the car from starting with my current key setup. He said the ECU and key may no longer be synchronised.

Has anyone experienced a similar issue with these ECUs or this type of system?

Thank you in advance for your help.

First video : The car start. 6F.SB
Second video : The car wont start. 6F.SH

I can provide more pictures or details if needed.

 

[jackwhoo]

Really? Does it even have an imobilser in 1993? Is there a "key" light on dash board?

 

[Nono21]

Really? Does it even have an imobilser in 1993? Is there a "key" light on dash board?

There is no key light or "CODE" light on dash board, so I'm not sure that the Rolling code theory told by the technician is true....

Does it need a manipulation to install the freshly repaired ECU ?

 

[The Panda Nut]

I would try asking a good local auto locksmith.

 

[jackwhoo]

No "code" "key" light etc makes me think the technician who worked on ecu is incorrect in saying imobilser is the problem.
Plus when you swapped with similar ecu it ran=no imobilser.

If ecu was repaired fully it should work as soon as refitted.

 

[Nono21]

No "code" "key" light etc makes me think the technician who worked on ecu is incorrect in saying imobilser is the problem.
Plus when you swapped with similar ecu it ran=no imobilser.

If ecu was repaired fully it should work as soon as refitted.

So, the problem must come from the technician ? He repaired the part of the ECU that make the plugs sparks, but it doesn't spray fuel in the motor.

 

[jackwhoo]

So, the problem must come from the technician ? He repaired the part of the ECU that make the plugs sparks, but it doesn't spray fuel in the motor.

Do you get sparks?

 

[ceecff]

6F from 1993 has not immo or connection to code thing. Seems ecu repair is not good. You could check with MES or IAW Scan 2 if ecu shows error.

 

[bugsymike]

If your ecu is a basic Weber-Marelli IAW SPi (singlepoint injection) I have the pin out tables to tell you what readings etc. to test. Though strangely my book lists the 1000 litre Panda 1.0 ie from 1991-96 as a Bosch Mono Jetronic |A2.2with an engine series number of 156 A2.246.
I does list the Weber on the Panda 899cc170A1046 do you have the engine series number and the make etc. of the original ECU?
Note as has been mentioned none have immobilisers from new!

 

[jackwhoo]

If your ecu is a basic Weber-Marelli IAW SPi (singlepoint injection) I have the pin out tables to tell you what readings etc. to test. Though strangely my book lists the 1000 litre Panda 1.0 ie from 1991-96 as a Bosch Mono Jetronic |A2.2with an engine series number of 156 A2.246.
I does list the Weber on the Panda 899cc170A1046 do you have the engine series number and the make etc. of the original ECU?
Note as has been mentioned none have immobilisers from new!

From photos it appears f.i.r.e engine

 

[Nono21]

Do you get sparks?

Yes, there is sparks. Just the fuel injection that is blocked. It can be heard when I switch quickly the 6F.SB with the 6F.SH (original).

 

[Nono21]

If your ecu is a basic Weber-Marelli IAW SPi (singlepoint injection) I have the pin out tables to tell you what readings etc. to test. Though strangely my book lists the 1000 litre Panda 1.0 ie from 1991-96 as a Bosch Mono Jetronic |A2.2with an engine series number of 156 A2.246.
I does list the Weber on the Panda 899cc170A1046 do you have the engine series number and the make etc. of the original ECU?
Note as has been mentioned none have immobilisers from new!

It's a IAW SPI yes

You are probably right about the immobiliser. As far as I know, my car never had any CODE immobiliser system from factory either. There is no CODE light on the dashboard, and the engine starts normally when using the other ECU (IAW 6F.SB).

The engine is the 999cc FIRE engine, I can check on the bloc in 2 hours.

 

[Nono21]

6F from 1993 has not immo or connection to code thing. Seems ecu repair is not good. You could check with MES or IAW Scan 2 if ecu shows error.

Ok good idea, i will buy something to read potential errors ! Thank you !

 

[bugsymike]

It's a IAW SPI yes

You are probably right about the immobiliser. As far as I know, my car never had any CODE immobiliser system from factory either. There is no CODE light on the dashboard, and the engine starts normally when using the other ECU (IAW 6F.SB).

The engine is the 999cc FIRE engine, I can check on the bloc in 2 hours.

Check these numbers and if so the pin outs should be correct for you to test readings. Sorry about the one on it's side.

 

[ceecff]

Supposing VIN I think I got it:

1S PANDA 4X2 MAQ 91
1000 SPI USA 83 WEBER
SPECIAL VERSION PRICE "SELTZ"
engine nº 4626011
injector 9947873
green/blue details
manufactured 20/1/1993

 

[bugsymike]

Supposing VIN I think I got it:

1S PANDA 4X2 MAQ 91
1000 SPI USA 83 WEBER
SPECIAL VERSION PRICE "SELTZ"
engine nº 4626011
injector 9947873
green/blue details
manufactured 20/1/1993

Do you know if that ties with Engine Series Number I work from in the photos above?

 

[jackwhoo]

I'm pretty certain we have worked out the "repair" has not worked / technician broke part of ecu.

 

[ceecff]

Do you know if that ties with Engine Series Number I work from in the photos above?

From your book photos (so good book!) more similar is 156A2246 but it's for Bosch ecu. Anyway AIW-SPI pinout seems good. OP engine if 4 speed should be 141C2000 or 5 speed 156A2000/2100.

 

[bugsymike]

From your book photos (so good book!) more similar is 156A2246 but it's for Bosch ecu. Anyway AIW-SPI pinout seems good. OP engine if 4 speed should be 141C2000 or 5 speed 156A2000/2100.

I actually bought the two books some years ago when I had problems with a Nissan Almera 1.6 that would keep immobilising it's self. I wired a complete extra 100 plus socket for a Nissan Micra 1.0 litre that didn't have an immobilser, so when it stopped I would un plug the Almera ECU and fit the Micra one, I then got a scan program and a 14 pin Consort? lead to fit the Nissan from Australia with a program for laptop that could access the immobilsier side and delete the error code so I could start it. In the end I traced the fault to an after market radio, interesting learning curve though.
The engine ran alright on the Micra ECU but a bit gut less.

 

[Nono21]

I actually bought the two books some years ago when I had problems with a Nissan Almera 1.6 that would keep immobilising it's self. I wired a complete extra 100 plus socket for a Nissan Micra 1.0 litre that didn't have an immobilser, so when it stopped I would un plug the Almera ECU and fit the Micra one, I then got a scan program and a 14 pin Consort? lead to fit the Nissan from Australia with a program for laptop that could access the immobilsier side and delete the error code so I could start it. In the end I traced the fault to an after market radio, interesting learning curve though.
The engine ran alright on the Micra ECU but a bit gut less.

Sorry to reply very late.

So, this is the information of my car :

FIAT Panda I 3/5 portes (141) 1000 i.e. Cat 45 CV / 33 KW Fuel 1987 - 1998 156 A2.246​

The modele on your book that match this is the Panda 1.0 i.e hoc.