P0303 Cylinder 3 misfire detected

bramlauwers · Aug 11, 2022

Hi all, greetings from Sweden. My father in law's precious Ignis MY 2004 with the 1.5 litre M15A 4-cylinder engine had started to judder earlier today while driving, and threw a engine light on the dash. When I connected the ELM327 OBD reader and Torque app, it said: P0303 Cylinder 3 misfire detected.

As I understand the firing order 1-3-4-2 would mean that the fault code "cylinder 3" in this case is the third in the firing order, in essence cylinder number 4, on the other side of the belts and pulleys.

Here's what I've done so far:
Checked all 4 spark plugs. They are NGK IFR6J11 Iridium which I've put in new only 17.000 km ago. Checked gap, and switched the plug from cyl 4 to cyl 1.
Ran engine again, same judder in idle, same fault code.

Switched the coil packs, so the one that used to sit on plug in cyl nr 4 now would sit on plug in cyl nr 2. Switched the other two wires to match the coil packs again and re-ran engine.
Same judder still, same fault code.

So now that cylinder 4 has ran with both a different plug and a different coil pack, it still seems to cause this judder and fault.

What would you suggest is the next step, would that be fuel injector?
I've never had a fuel injector out before, is that easy to test and remove?
Other suggestions?

Many thanks!

aquanaut20 · Aug 11, 2022

The P0303 Is the third cylinder from the pully end of the engine, has nothing to do with the firing order.. (cylinders are designated Front 1-2-3-4 Rear)

You have been working on the wrong cylinder...

What tools do you have and what exactly is your skill level ?

2000IGNIS · Aug 11, 2022

aquanaut20 said:
cylinders are designated Front 1-2-3-4 Rear

You have been working on the wrong cylinder...

I agree, although I don't know how that tester described works.

At least the coil packs have been ruled out, somewhat, but they can often be an issue. At least with cylinder 3, you could unplug it and test it with a couple of screwdrivers to make a small gap from the valve cover and see if there is spark (NOT near the wiring harness!).

2013GV · Aug 12, 2022

Have you changed the plug leads? Or just the coils? If you have changed coil locations, and plugs, leads are next. Then you are into checking fuel delivery if the misfire doesn't either move with the lead or go away.

fordem · Aug 17, 2022

The #4 plug has been switched with #1, but the possibly defective #3 plug is still right where it was...

bramlauwers · Aug 27, 2022

I'm glad the issue has been resolved now. The car runs great once again, with smooth idle and quick throttle response.
I got frustrated when the coil and spark plug switch did not have any effect, so I ended up buying these items online for a good price (total approx 160 EUR which was the same amount a local workshop had offered to charge just for a initial fault diagnosis, so I figured it was worth the try):

new ignition coils - 2 pieces - Delphi
new ignition leads - 2 pieces - NGK 1801
new spark plugs - Bosch iridium

After installing above it was all resolved. I don't know if it was the coils, ignition leads or perhaps even the plugs that might have caused the issue, even though the old plugs were NGK IFR6J11 Iridium with only 17.000 km. I'm just pleased it was only ignition related and easy to resolve.

2000IGNIS · 2025-09-23T22:30:34-0400

bramlauwers said:
After installing above it was all resolved. I don't know if it was the coils,

I think it was one of the coil packs ??. You can find out for sure if you want - swap the old ones in, one at a time, test drive it and carry the tools and gloves if problem returns.

haroldjonie10 · 2025-09-22T03:15:21-0400

Hi, what brand of Elm327 you are using? I appreciate your response.

P0303 Cylinder 3 misfire detected

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