I have a punto 1.2 2001 reg and it has just had the head gasket changed.

Then it gradually but quickly developed another fault with the engine light code set to on so I bought fiat scanner and elm 327 to read the code.

it runs v.poorly

the code

p0352 - ignition coil (3)
explanation given is software is [ ECU ] received very low signal from sensor!

I don't understand.. what sensor?

With the engine running I clear the fault code and for a few seconds it runs fine then the code re-appears and back to running rough. I presume its shutting the injector down to protect the cat.

I have changed both coil packs and swapped them over with no avail.
I have changed plugs with no difference
I have but the spark tester on each and they are sparking fine

If I am taking the software's words literally its talking about a sensor with a low signal to the ECU but I cant think what this could be/mean

I have read about the ecu's can go down but I have checked the signal at the coil end and it appears to be fine ( 12v constant signal and pulsating negative switching signal )

I don't understand what could be causing this problem so hoping somebody could give me ideas or maybe its something you have come across before that you have fixed?

Thanks for reading I so hope you can help its driving me mad and I don't want to be spending money that I haven't got...

I promise to donate if the answers lead to its fix!

Why not donate anyway?

Could be a failed coil driver in the ECU. Does the car misfire?

Have you tried swapping HT leads?

Well I have tried HT leads no difference at all

Is the coil driver in the ECU you mention something that can be reprogrammed or does it need new parts?

I donate my knowledge and pay cash when I learn something I just think this is a fair method thats worked for me on many forums over the years, but I understand your point too.

https://www.fiatforum.com/punto-guides/52068-punto-coil-ecu-checks.html

Swapping the coils over with the same result shows it's not a coil issue, and suggests it's a failed ECU (running on 2 cyls?- the Coil 2 error will mean there's no spark on cyl 2 & 3).

There's no 'sensor'. It's just a poor translation/description in the scanner software.

This is why I am a little uncertain as to it being the ecu becasue it does fire on all of the plugs and I have done the ecu signal test and determined the +12v constant and negative switching steady pulse.

The error code seems to cut the fuel to the injector which is why it doesn't run correctly. I just cant fathem whatscausing the code to kick in.

Donny1 said:

Is the coil driver in the ECU you mention something that can be reprogrammed or does it need new parts?

Click to expand...

Will need a replacement ECU or recon of the current one.

Donny1 said:

This is why I am a little uncertain as to it being the ecu becasue it does fire on all of the plugs and I have done the ecu signal test and determined the +12v constant and negative switching steady pulse.

Click to expand...

You've discovered the Signal is there, but is it correct voltage etc? Sorry I can't be much help, but not had the same on any coil pack faults I've had in the past.

Any advice is help! I haven't checked the voltage to be honest. I will check tomorrow and do my best with a digi meter and freeze frame the Volts.

Will compare witht he working set and see what it compares with.

Would be interested to know if the signal etc is their would this mean that the drivers are ok but possibly corrupt signal?

Other tests that I am going to do is the Dark room test, jump lead the earth terminals and run another wire from the ecu to the coil pack direct and see if this makes a difference.

Dont suppose anyone knows what pins on the ecu are used to connect to the coil pack? Would be greatfull for this info....

Will post my findings tomorrow.

Thanks so far

Thought I would share this info that I have found on another forum, it seems like a good educated explination, but will still test as above 1st before slapping 120 quid on a ecu!

it a common failure on this type of ECU.

how to know this:
1/ on DIAG you have one of the two faults codes:
P0352 DTC (Ignition Coil B) or P0351 DTC (Ignition Coil A)
2/ replacing the related ignition coil do not resolve the problem.

at this time you can be sure that this is the ECU.
if your ECU is 59F.M3 you have to check hardware:

if HW < 100 --> (MOTOROLA MCU) not fixable , replace ECU
if HW > 100 ---> (ST MCU) can be repaired.

note that you can replace HW003 by HW303 but you have to virgin it before

Hope these diagrams help

Weak signal - Well IIRC the Crank Sensor gives the Timing for the Spark
So surly weak signal - is going to be the Crank Sensor - possibly been too far away - so its only see'ing a partial signal

Ziggy

Thanks for the diagrams will come in handy...

Interesting point about crank sensor but wouldn't/shouldn't this be picked up by fiatscan diagnostics? either way will put it on my list and give it ago.

going to spend a few hours now and will post my findings later!

Well I spent a few hours and nothing seems to be wrong with anything.

Coil packs are getting the correct voltage and the pulses are identical from a & b so the only assumption has to be the ECU so its out and ready for a new one!

Can anyone confirm if they need to be programmed to the car, I have read that most do but the one with the 003 code doesn't?

I am coming late to this, so please bear with me.

Did this missfire only occur after the headgasket change?

Cheers

D

To be honnest its hard to say because I bought it with the HG problem.

It seemed to run fine though when head was changed for around 20 miles

Just to recap slightly, when I clear fault code as engine is running, for a second or so it runs ok.

From memory, the usual fault with the problem ECUs is a random misfire. If you have the big ECU that sits on the wing, it's extremely unlikely to be an ECU issue. (There's lotzs of stuff here about identifying and even repairing the ECUs.)

I would do a compression test just to rule out the HG (humour me!).

Although I've never seen it, I'd guess that a TDC sensor on its way out might just trigger this error.

Its the small ECU that sits on the engine block, seems to be a common fault, on the 003 ECU.

I doubt that a HG fault would trigger the low signal code.

TDC was faulty then wouldn't it cause coil banks A+B to be low signal?

I want to try flashing the ECU but I only have the KPW2000 and I cant find the correct and I spent hours searching this forum.

ECU IAW 59F.M3 HW003