Technical Stilo Fault Codes....P0352 P0353

[Johno933]

One for all you technical wizards......2 Fault codes keep appearing P0352, P0353.....Ignition Coil B and C primary circuit....

Have Diagnostic tool so i just keep switching it off, but it is starting to annoy me, want to find the cause...

It Only Flashes on when over 80MPH (4500rpm)for more than a couple of min. There Is NO misfire, NO lack of power. car runs fine. Just the |Dammed Beep Beep Beep._ engine Fault.

Am thinking it is cheap coil pack related problem I.E got 3 unbranded coils and 1 branded coil...spark plugs are new (1 week) and all coils No more than 4 months old.

Switched coil packs over - No change

Any Ideas????

 

[Deckchair5]

What engine is it?
I presume you swopped coils from a good place to a bad place ie cyl 1 to cyl 2 with no change in symptoms? And if you did then you've proved no problem with the coil itself

• P0352 - Ignition Coil 2 Control Circuit
• P0353 - Ignition Coil 3 Control Circuit

P0353 and P0353 are ignition control circuit failures rather than the coils themselves so I'd look for problems at ECU and from ECU to those coils.
I'd check ECU earth and wiring from ECU to coils
Check for 12v at the coils and integrity of the signal earth line from coils back to ECU

Haven't recently had a cambelt change have you?

 

[Johno933]

Thanks for the input...

Have switched coils 1 with 2, 3 with 4...still same fault. (coils OK)

Wiring from ecu to coils seems fine - got voltage.

Was reading a thread about earth faults...Could that be where the problem lies, and if so which one would be suspect and Where is it located.

Am going to pysically check them all tommorow (the ones i can see) and run a new lead to any that look suspect. (With clean up) belive the ECU has 2 earthing point. Is that correct?

Just to add. It is a 1.6 Active 52 plate.....and on the drive home from work Have managed to find the exact fault trigger....

It happens when you come off the accelerator pedal while going over 80mph. while still accelerating it is fine up and above, but as soon as you release the pedal...Beep Beep Beep. Get home 3 restarts later and the fault has cleared itself.

Cam belt not been changed yet...only 61000 on the clock, was planning change at 65000

 

[Deckchair5]

Well that's a nice bizarre fault

If you can initiate the fault with those engine rpm circumstances every time then I would forget poor contacts ie bad earth or poor connections as that won't be affected by a set car/engine speed

It's so bizarre to affect just the same 2 cylinders that I'd focus on engine speed type sensors of rpm sensor and cam position sensor. But the rpm sensor would affect all cylinders so you're just left with the cam sensor

Can you check what rpm you are doing when it happens and then simulate it in 4th gear too? If you can then you know you're looking at an engine rpm/cam type sensor fault


The ECU earth is here circled in red but to check the earth then all you need do is have the engine running, multimeter set to volts and check voltage drop between the ECU mount where I have the probe here and the battery earth. You should see near 0v and definitely not more than 0.5v. That's it, earth checked

It's up to you but you're well overdue a cambelt change on age alone

 

[Johno933]

I see where you are going with your logic.

seems very bizarre but happens almost on a daily basis on the way back from work.

Will get the car out on the bypass tomorrow and try to Trigger it if 4th gear....

Watch this space.

The really embarrassing thing is that i work in a Garage, but no one knows Fiats and their Mystery Faults.

 

[Johno933]

Ok, Just back from a wee road Test.....on motorway 4th Gear rpm reading 3800ish release the accel pedal....Beep Beep Beep same in 5th gear between 3800 and 4200 RPM

Same Fault codes P0352 and P0353

No change in Engine Tone or Power Loss

Can Not trigger the fault when stationary by revving the engine....seems only to be when Driving..

Thoughts....appreciated

 

[Deckchair5]

Ok I'd do a voltage drop test on the ECU as explained above to check out the ECU earth then I'd inspect very carefully the wiring from the ECU to the problem coils looking for fraying, chafing, anything that would provide a short across wires or a short to the engine block. Also check the coil connector pins for widening and poor contact with the coil and a poor contact could also exist at the ECU end