Technical Punto 1.2 8v 2004 code P0352 - Bad battery?

[akyttala]

Is it possible that bad battery can cause code P0352, Ignition coil B primary/secondary circuit malfunction?
Engine runs normal, no misfire and pulls strong as 1.2 8v always.

Engine light came first time November at start, I drove to work normally, read codes, changed both coils there, resetted code - problem solved.
Today it came again at start. Car worked normal next ~50km to home and after clearing code it didn't come back.

Battery is probably going bad as power streering light have lighted this winter few times when it is cold mornings, -10'c or so. Every time light went away with new start. I have had car over 15 years and steering light in cold days have always indicated bad battery and have fixed with new battery for next 4-5 years.

But coil code is a new symptom and I was wondering if it can caused by bad battery. Is it even possible?

Other possibility is maybe failing spark plug. I have changed them last october, about month before coil code came first time, but if spark plug was failing it would probably also affect engine running. Now engine light just comes at start but there is no problems of any kind. I wouldn't notice difference if engine light didn't come on.

 

[GrandePunto PL]

And what's the problem here, what's your "struggle"? To diagnose a battery? Is it rocket science?
If it's proper (old-school), serviceable battery, you check the electrolyte level and density (how strong the acid is).
No electrical test will ever tell you what is exactly wrong with the battery (which cell is failing and how).

Check existing content about P0352 code in Fiat cars. Forum, Google, YouTube...
Random results: https://www.actronics.co.uk/news/diagnostic-help/how-to-fix-fiat-p0352-fault-code
https://www.ecuedit.com/fiat-punto-ecu-fail-p0352-t12124

If it's not battery, check wiring (all wires and plugs involved in ignition system and the power delivery, fuses, relays, "ground/earth").
If cables etc. are OK, then it's an ECU...

 

[akyttala]

And what's the problem here, what's your "struggle"? To diagnose a battery? Is it rocket science?
If it's proper (old-school), serviceable battery, you check the electrolyte level and density (how strong the acid is).
No electrical test will ever tell you what is exactly wrong with the battery (which cell is failing and how).

Check existing content about P0352 code in Fiat cars. Forum, Google, YouTube...
Random results: https://www.actronics.co.uk/news/diagnostic-help/how-to-fix-fiat-p0352-fault-code
https://www.ecuedit.com/fiat-punto-ecu-fail-p0352-t12124

If it's not battery, check wiring (all wires and plugs involved in ignition system and the power delivery, fuses, relays, "ground/earth").
If cables etc. are OK, then it's an ECU...

My "struggle" is code P0352.
Battery is not the main problem, I know it is old enough to be bad.
I just want to know if it's possible to bad battery cause code for coil pack before I try anything else.

I know there are lot of possible problems from sparkplugs and HT leads to ECU failing.
Searching forum didn't help. I already read over 10 different Punto/Panda P0351/P0352 threads and none of them weren't helpful. Nobody mentioned battery and also majority have misfire or other problems when code exist. My Punto works like a Swiss clock, but have generated code P0352 two times.

 

[Mike1alike]

I say a bad battery cannot throw the P0352 code. A bad ground connection could, maybe.
I had the P0351 error (which is the same, just for the other coil) and I fixed it by replacing the ECU. Prior to that error I ran the car with bad coil, I discovered it shortcuts inside after the error started appearing. It took kind of a long time since the error first appeared until the car was undriveable. Technically, the shortcut burns the transistors (I think there are 6 transistors) inside the ECU, responsible with the coil power feed. Usually 1 gets toasted and that is enough, the rest follows in time. Mine just showed the error first, then slight hesitation on how the engine ran, than bigger and bigger until engine ran only on 2 cylinders. It was very puzzling because the problem wasn't showing all the time, after it started. Had moments when engine was running like a good clock, like yours, then it wouldn't, then good again. Finally, I identified it was the ECU and putting another ECU was the fix.

 

[akyttala]

I say a bad battery cannot throw the P0352 code. A bad ground connection could, maybe.
I had the P0351 error (which is the same, just for the other coil) and I fixed it by replacing the ECU. Prior to that error I ran the car with bad coil, I discovered it shortcuts inside after the error started appearing. It took kind of a long time since the error first appeared until the car was undriveable. Technically, the shortcut burns the transistors (I think there are 6 transistors) inside the ECU, responsible with the coil power feed. Usually 1 gets toasted and that is enough, the rest follows in time. Mine just showed the error first, then slight hesitation on how the engine ran, than bigger and bigger until engine ran only on 2 cylinders. It was very puzzling because the problem wasn't showing all the time, after it started. Had moments when engine was running like a good clock, like yours, then it wouldn't, then good again. Finally, I identified it was the ECU and putting another ECU was the fix.

Thank you.
Did your engine have misfires etc. from beginning of problem or did it generate code even when running fine?
I was little worried that it is ECU as it is quote expensive. It costs more than value of the car.
Do you know if ECU can be bought from scrapyard and pair it with new car with Multiecuscan or do I need to buy "resetted" ECU from shop that fixes ECUs?

 

[Mike1alike]

As I mentioned, at the time the coil was bad and I didn't knew that. That started the misfire. With the new coils it wouldn't throw error code when running fine, or at least I didn't notice.
New ECU is expensive, but I got one from a scrapyard, really good price, I think it was about 70 euros. They have an "ECU Department" and sold it virginized, with IMMO details deleted. I just connected it and it worked instantly. When the key is first time turned on (after deleting the data on ECU), ECU reads and stores the info from the chip in the key and that's the "pairing". You cannot do it with Multiecuscan, they use other tools to delete the info. I checked now and I see that they're still in business and they still have the model I got, at the same price. I got mine in 2022. This is the page (translated) with their add, if you ever need to buy from them I can help you if you need.

But that is the worst case scenario for that error, ECU being toasted. Before buying another ECU you need to make sure the one you have is damaged.
First thing, swap the coils. If the error changes to P0351 it means the coil is damaged and the ECU is fine.
And anyways, you should put a good new battery on the car and make sure the grounding line is ok.
Also, you should make sure the other components from the electrical circuit are working. Besides spark plugs, the leads are an important part that can cause this error. How old are your leads? And what plugs did you put, ngk or something else?

And in the end you can test the ECU using a multimeter. But as long as the engine is running ok, testing would give you good results. At first, ECU only has rare moments of not working ok and those are recorded as this error. You have to manage to catch it on those moments to test it and that's pretty difficult. But in time, if you leave it like that, it does get from bad to worse and you will even see it on the multimeter. Here's a photo with instructions on how to test it.
At mine, I also tested it with a testing lamp when the engine wasn't running properly. I probed the lines that go to coils and started the engine. And the (+) is always on, 12 V, but the (-) one is the one that goes intermittently. On the good circuit (coil no. 2) the lamp lit intermittently the 12 V light, on the other one (coil no.1), only the 6 V.

 

[akyttala]

As I mentioned, at the time the coil was bad and I didn't knew that. That started the misfire. With the new coils it wouldn't throw error code when running fine, or at least I didn't notice.
New ECU is expensive, but I got one from a scrapyard, really good price, I think it was about 70 euros. They have an "ECU Department" and sold it virginized, with IMMO details deleted. I just connected it and it worked instantly. When the key is first time turned on (after deleting the data on ECU), ECU reads and stores the info from the chip in the key and that's the "pairing". You cannot do it with Multiecuscan, they use other tools to delete the info. I checked now and I see that they're still in business and they still have the model I got, at the same price. I got mine in 2022. This is the page (translated) with their add, if you ever need to buy from them I can help you if you need.

But that is the worst case scenario for that error, ECU being toasted. Before buying another ECU you need to make sure the one you have is damaged.
First thing, swap the coils. If the error changes to P0351 it means the coil is damaged and the ECU is fine.
And anyways, you should put a good new battery on the car and make sure the grounding line is ok.
Also, you should make sure the other components from the electrical circuit are working. Besides spark plugs, the leads are an important part that can cause this error. How old are your leads? And what plugs did you put, ngk or something else?

And in the end you can test the ECU using a multimeter. But as long as the engine is running ok, testing would give you good results. At first, ECU only has rare moments of not working ok and those are recorded as this error. You have to manage to catch it on those moments to test it and that's pretty difficult. But in time, if you leave it like that, it does get from bad to worse and you will even see it on the multimeter. Here's a photo with instructions on how to test it.
At mine, I also tested it with a testing lamp when the engine wasn't running properly. I probed the lines that go to coils and started the engine. And the (+) is always on, 12 V, but the (-) one is the one that goes intermittently. On the good circuit (coil no. 2) the lamp lit intermittently the 12 V light, on the other one (coil no.1), only the 6 V.

I have already changed both coils at november, when code first time was present. It was same P0352. Really bad luck if exactly new B-coil is defective.
It's not very hard to change them though so i will do it.
HT leads are changed when I changed spark plugs not last but second last time, so under 50000 km ago.
Plugs are Denso Twintip which I have used at least 6 times before, maybe for 250000km and they have worked good.

Unfortunately my own parking space is outside and its cold again (when it is not cold in Finland..) but next tuesday evening I can get car in garage at work. I will first check battery ground to body and gearbox, wires between ECU and coil and HT leads.
Now I recall I had problems to get 3. cylinder HT lead removed last time I change plugs, so now I started to think if it is damaged. B-coil is the one igniting 2. and 3. cylinder?
I may have new set of NGK wires somewhere. They are by the way best lenght HT leads I have found for Punto.

I really hope I find something wrong with wiring etc. and ECU is still working. I have changed plugs but also coils and HT leads periodically to "protect" ECU as I have heard earlier about these ECU problems.
But if ECU is the problem, I will ask your help if you can get it cheaper. Here it costs 300-500euros. Value of 21 year old Punto with 370000km at clock is maybe same, but it has been really good and realiable car and I have planned to keep it till the end of world. I have looked for new car for few years to leave Punto as second car but unfortunately it is really hard to find good Fiats in Finland. They have sold only handful of them after ~2012 new importer/seller/service spoiled whole thing and importing Fiat stopped for few year. When they started to sell it again nobody didn't have any will to sell Fiat, no commercials, no demonstration cars to test, nothing. So Fiat after MY 2013 is quite rare and hard to find.
Sorry for offtopic and thank you. You have been really helpful!

 

[Mike1alike]

Yes, Coil A/1 does 1 and 4. Coil B/2 does 2 and 3.
Tip to easily remove the leads: never do it when they (and the engine) are hot. The silicone tightens when getting hot and that makes it almost impossible to get the leads out without damage. But they do come off very easy when they are not heated. A twist (clockwise or counterclockwise) before pulling also helps.
NGK RC-FT 1208 is very good and also is Magneti Marelli MSK58 - 941095100582. Now I have MM, I had the NGKs before.
By their length, the leads go: the longest 2, 1, 3, 4 the shortest. If you put them where they are supposed to go (those plastic clips) they are the perfect length.

 

[Mike1alike]

By what you are saying I'm guessing (and hope for you) that the ECU is ok. And regarding what you asked before, I remembered, mine wouldn't throw the code if I wouldn't first feel it on the engine. I did check many times those days and that is how it was, the code was shown only after engine ran not ok. Also when the code would appear, the EML light would pop up, so I could see it instantly.
Can you remember when your code first started appearing? Like before replacing the coils and pulling the leads or after. One easy way to test the leads is that looking at the engine running in the dark. If something's wrong, you'll see sparkles around the lead, like a Christmas tree they say. It's not conclusive, because the damage can be on the inside, cable pulled out of the connector, but if you'll see the sparkles I think you will feel like it's Christmas, knowing the ECU is alright. Fingers crossed!

 

[akyttala]

Yes, Coil A/1 does 1 and 4. Coil B/2 does 2 and 3.
Tip to easily remove the leads: never do it when they (and the engine) are hot. The silicone tightens when getting hot and that makes it almost impossible to get the leads out without damage. But they do come off very easy when they are not heated. A twist (clockwise or counterclockwise) before pulling also helps.
NGK RC-FT 1208 is very good and also is Magneti Marelli MSK58 - 941095100582. Now I have MM, I had the NGKs before.
By their length, the leads go: the longest 2, 1, 3, 4 the shortest. If you put them where they are supposed to go (those plastic clips) they are the perfect length.

By what you are saying I'm guessing (and hope for you) that the ECU is ok. And regarding what you asked before, I remembered, mine wouldn't throw the code if I wouldn't first feel it on the engine. I did check many times those days and that is how it was, the code was shown only after engine ran not ok. Also when the code would appear, the EML light would pop up, so I could see it instantly.
Can you remember when your code first started appearing? Like before replacing the coils and pulling the leads or after. One easy way to test the leads is that looking at the engine running in the dark. If something's wrong, you'll see sparkles around the lead, like a Christmas tree they say. It's not conclusive, because the damage can be on the inside, cable pulled out of the connector, but if you'll see the sparkles I think you will feel like it's Christmas, knowing the ECU is alright. Fingers crossed!

First of all, I think (I hope?) I found the problem. HT lead of 3. cylinder won't "click" in place. I removed it and tried with old sparkplug and indeed it won't click when pressed on end of plug. I need to push it 3-4mm more after insulator hits plug to hear contact click in place. It's not possible to push so deep when sparkplug is installed in engine as there is little "hollow" around plug. I attach picture with old working cable clicked on place and my 3. cable pushed much deeper and still no locking on place.
This is maybe the reason to code? I wonder how it run so good if contact with plug and lead is so bad.
I remember I had really hard to remove 3. lead when changing plugs. All other were easy to remove but this was really hard. Probably I have damaged it somehow and connector inside rubber/silicone/whatever it is have loosen and started moving when removed. I hope my ECU haven't broke because of this. It is probably harder for coil to generate spark if contacts are bad but I don't know if it affects ECUs transistors in any way.

Background info is maybe not needed anymore, but here it is anyway. I have changed spark plugs October 2. 2024 at 359500km. First time code P0352 came November 27. 2024 at 362000km. No misfires, no problems running. I resetted code and it didn't come back, but next day I changed coils just in case to protect ECU. Everything was fine until last saturday, March 8. 2025 367600km, when engine light came on, again no misfiring or any problems. Code reader gave again P0352, I resetted it and it didn't come back. Today I have driven ~200km without problems. I was able to get car inside about hour ago and first removed wires and HT leads from coils, everything was looking good and clean so I reattached everything and then decided to remove HT leads other ends starting with 3. as I recalled it was hard to remove last time. It really was too easy this time. I tried to put it back but no "click" at end, so I removed it, tested with old plug and then tested old plug with old cable and noticed problem I wrote above.

I will buy new HT leads now as I can't find set I thought I have already and hope next 30000km to next sparkplug change go without problem. I think I will change leads everytime I change plugs in future. They are not that expensive especially when compared to price of ECU.

Thank you very very much! It was really good to know that problem can be also in HT leads instead of coils, wiring between coils and ECU and ECU itself.
Also your tip to remove leads when engine is cold is really welcome. I have always serviced warm engine and changed plugs while oil is draining. I think it is because of old myth that sparkplugs are easier to remove when engine is warm.

Here is pictures.

Old sparkplug "clicked" in place with spare lead:


Old sparkplug with my 3. lead not "clicked". Still need to push 3-4mm deeper for contact to "click" in place.

 

[Mike1alike]

I'm very glad you've fix it and that the ECU is ok.
I don't think the lead is damaged, I think you can stil use it. What happened is that you pulled of it while the silicone protection was "glued" to the plug and the cable (+contact) moved upwards inside the silicone protection. But is not damaged. You can push it back, having it disconnected from the plug, you'll see that it moves relatively easy. And that's normal. When it gets heated it tightens.
So there you have it. That gave you the code, imperfect contact at spark no. 3. ECU is sensitive and picks up any abnormal value. ECU didn't get damaged as you didn't put any stress on it by shortcut on the circuit, you just had the imperfect contact that unbalanced what it reads on the circuit. The engine ran without problem because it was firing on all cylinders although the spark on no. 3 was a little dimmer.