Check engine light + juddering, "unknown fault"

[carlove]

Hi

Was driving to Edinburgh today when on the A1 my car started juddering for a few seconds, and the check engine light came on. It then drove fine. However, concerned about driving another 150 miles I pulled off and a Halfords Autocare kindly plugged it in to see what came up, and it came up with an "unknown error", not sure what that means, he said it'll be fine to drive and cleared the code.
After another 10 miles or so the car had another juddering episode and EML was back.

I kept driving and it drove perfect, until about 10 miles from Edinburgh where it had another juddering episode, before driving perfect again.

Any ideas? My initial thought was a misfire, but I'm not sure what they feel like, and I don't think that would do a "unknown error" code. The thought of a DPF problem crossed my mind, but I think the DPF has its own warning light.

I'll be booking it in at my local trusted garage when home, but kind of wondering if I should get it checked over here.

It's a 2017 Astra 1.6 diesel with 120k miles, of course last week I said how it's never let me down!

[stevieturbo]

There is no such thing as an unknown error.

Take it to a competent mechanic, and not some fool with a cheap code reader.

[carlove]

stevieturbo said:

There is no such thing as an unknown error.

Take it to a competent mechanic, and not some fool with a cheap code reader.

Yep, first time my cars entered a Halfords. It's booked in on Monday at my trusted mechanic for proper diagnostics. He reckons its going to be a glow plug issue, which I think fits the bill.

Just gone to get some dinner and the engine light has gone, so had a bit of an extended drive and it drove perfect with no reccurence of the juddering, odd. I'll still have it checked over when home.

[E-bmw]

It won't be a glow plug as you had been driving for some time when the problem came up & as above there is no such thing as an unknown fault, just one that their cheapo system doesn't recognise.

Let your preferred place diagnose it properly & let us know what they said.

[stevemcs]

Glowplugs are common on these but they won't cause a misfire, if your in the AA/RAC call them out and get them to scan it.

[carlove]

It's had some diagnostics in Edinburgh, and come back as "cylinder 4 system balance" error. Spoke to my local garage, likely cause is a bad fuel injector, they said a fuel injector can be tricky to remove as they need to be very careful, so they sometimes have to have a second company if it needs compressing(or decompressing, forget which), so it can be a costly job.

Bit of a damper put on my mini break

Why did I have to say "it's never let me down"?

[stevieturbo]

injector seems more plausible...and on some vehicles, yes they can be a nightmare.

At least they're open and honest about it and have the wit to recognise it may need someone who specialises in that so as to minimise risk.

[carlove]

stevieturbo said:

injector seems more plausible...and on some vehicles, yes they can be a nightmare.

At least they're open and honest about it and have the wit to recognise it may need someone who specialises in that so as to minimise risk.

I've been using them for years, always honest and helpful. Always glad to find a good garage.

[carlove]

The car made it back from Edinburgh, and my local garage had it in today for a full diagnostic. The good news was the fuel injectors were fine, but there was a large build up of carbon, which was causing the fuel injectors to struggle. My mechanic recommended a carbon clean, a service he doesn't offer, but I've booked it in at a local garage that does do it, the chap from the garage was very honest, and said carbon cleans aren't always the answer and may not solve the issue, but he did his sales pitch and said on a higher mileage diesel that's not running great, even if it doesn't fix the issue it can still be of benefit.

I'm in two minds really, I've seen carbon cleaning on Facebook before, but kind of wrote it off as a bit of a scam, but for £120 and my mechanic recommending it I'll give it a go, and if the issue comes back I'll take it from there. I did see the ones on Facebook that come to your house and do it for about £70, but I kind of think if someone is messing with the engine using a reputable garage that charges a bit more appeals more to me.

[stevemcs]

I’ve never known carbon clean work, as an example how’s it supposed to shift this

[stevieturbo]

carlove said:

The car made it back from Edinburgh, and my local garage had it in today for a full diagnostic. The good news was the fuel injectors were fine, but there was a large build up of carbon, which was causing the fuel injectors to struggle. My mechanic recommended a carbon clean, a service he doesn't offer, but I've booked it in at a local garage that does do it, the chap from the garage was very honest, and said carbon cleans aren't always the answer and may not solve the issue, but he did his sales pitch and said on a higher mileage diesel that's not running great, even if it doesn't fix the issue it can still be of benefit.

I'm in two minds really, I've seen carbon cleaning on Facebook before, but kind of wrote it off as a bit of a scam, but for £120 and my mechanic recommending it I'll give it a go, and if the issue comes back I'll take it from there. I did see the ones on Facebook that come to your house and do it for about £70, but I kind of think if someone is messing with the engine using a reputable garage that charges a bit more appeals more to me.

That makes little sense.

And the only way to properly clean the inlet system on vehicles like that, is to take it apart completely, and clean it. That may require lots of elbow grease or some sort of media blasting type cleaning.

Anyone spraying st into the intake and saying it will clean, are just idiots conning you out of money

The crud that builds in intakes as the above picture shows can be solid as rock and take some serious effort to clean.