Fiesta Mk7 P0302 error code

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andyj941

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Hi we have an Mk7 Fiesta, 1.25 petrol, with the engine warning light on and a P0302 code when I plug my reader in. I've swapped out the spark plugs, ignition leads and coil pack to no avail. A garage did a compression test for me which was OK, and got some petrol system cleaner to put in the fuel tank. I've done this and filled it up with the good stuff (normally it's always supermarket fuel) and driven it for a couple of days but after clearing the code the light comes back on. Not sure if the cleaner has had chance to get to work on the injectors yet.

What I have noticed is that when the AC is on, and under acceleration, there is a short sharp squeak which I'm wondering could be a belt slipping. Sounds like it's coming from the front drivers side. When the AC is off this noise never happens. Could this be a cause of the P0302 code?
 
Your fault code refers to cylinder no.2 misbehaving.....as you’ve fitted a new coil and had a compression check done I’d consider replacing the fuel injector itself.
Is the car misfiring - especially on tickover?
I can’t see this being related to the slack drive belt, but this needs attending to.
John :)
 
Only in my experience, but with some vehicles - French cars in particular - it's recommended to replace all of the pencil coils rather than just the faulty one, for reasons unknown to me.
Original equipment coils are recommended every time, and I can't comment if they are coded to your car.
You can check the injector resistance - look for around 18 ohms on each one.
John :)
 
This car doesn't have individual pencil coils, all 4 are on the same coil pack.

Is it worth doing the Italian tuneup suggestion? I'm just worried it could cause more damage by driving it. Got it booked into a garage on Thursday next week.

Had the plugs out again and switched them around, shone a torch into the plug holes and they were clean.
 
Ah, it’s the Zetec engine then.
If the plugs are the same colour, I’d wait for a diagnostic check - it could be a catalytic converter issue if it’s been replaced by a non standard item.
John :)
 
Yes they all look like this:
20220203_161329.jpg
 
Hi so unfortunately the engine had to be stripped down and lots of work done including new exhaust valves fitted as the old ones had burned out. A very unexpected and unwelcome cost. They reckon this problem is on the increase since the new E10 petrol was introduced.
 
Yet the garage performed a compression test originally - which was fine.
Hmmm. I wonder what was actually wrong with it?
John :)
 
The first was a garage I've never had much luck with but they are pretty much next door. Given the length of time they had the car, I'm not sure they actually did a test. Had it for a week, just gave me a bottle of petrol system cleaner. Second garage tested same day and gave me actual values, at least they said they had!
 
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