Engine light came on
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Discussion

sunnydude959

Original Poster:

907 posts

158 months

Saturday 31st January 2015
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Hi Guys.

I had a small issue with my car this morning and I was wondering if you guys could give some advice.

Basically, I started my Merc CL63 AMG (5.5 biturbo) this morning and after just driving down the road, the engine light came on. I then pulled over and rang up mercedes "MB Contact" in the phonebook (sort of like BMW assist kind of thing), and he said that it should be fine to drive to the dealership on Monday.

I then got my bluetooth diagnostic OBD adapter out, plugged it in, ran the app on my phone and it came up with the code P0300 which is engine misfire not attributed to a particular cylinder(s), apparently.

As he said it was fine to drive, I decided to wait for the engine to warm up to temperature, and then put my foot down for a short amount of time (all speed limits and laws were adhered to!). I then stopped outside a shop to get something, and when I got back in my car, the engine light had extinguished.

Is it still worth going to a Merc dealer about it? Or was it simply a blip in the system? I haven't had the light come on again since this morning.

Sunny.

Northernchimp

1,282 posts

163 months

Saturday 31st January 2015
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Warning lights are frequently intermittent but rarely come on once for nothing. If its out of warranty take it to a specialist or prepare to have your pants pulled down by an MB dealer.

anonymous-user

85 months

Saturday 31st January 2015
quotequote all
Misfires can happen for a lot of different reasons. If it doesn't come back I wouldn't worry about it. If it does then get it investigated.

sunnydude959

Original Poster:

907 posts

158 months

Saturday 31st January 2015
quotequote all
charltjr said:
Misfires can happen for a lot of different reasons. If it doesn't come back I wouldn't worry about it. If it does then get it investigated.
Thanks guys.

I fergot to mention that my car is going in for a service on Wednesday (almost forgot myself!), so I guess I could ask them to take a look at it. If they charge me £50 or so for diagnostics, then thats fine I guess. I'm more scared of the 3 and 4 digit values of money!!

Jasandjules

72,664 posts

260 months

Saturday 31st January 2015
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It might also be something silly like a small hole in the exhaust causing the computer to get the readings wrong?!?

northwest monkey

6,370 posts

220 months

Saturday 31st January 2015
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Was it misfiring or did the computer just say it was?

I had something similar a couple of years ago where the EML came on & off intermittently & it ended up being a coil pack.

sunnydude959

Original Poster:

907 posts

158 months

Saturday 31st January 2015
quotequote all
northwest monkey said:
Was it misfiring or did the computer just say it was?

I had something similar a couple of years ago where the EML came on & off intermittently & it ended up being a coil pack.
It wasn't misfiring from what I could feel/hear, although I may well be wrong.

xxChrisxx

538 posts

152 months

Saturday 31st January 2015
quotequote all
If you can't feel it. It's not a bad misfire. id be temped to just leave it and see what happens. Unless you can get it scanned for free of course.

Random and intermittent emls are not something to worry about.

When you say service is it for oil only, or something more? If its due filters and plugs for example, that could very well fix it.

V88Dicky

7,373 posts

214 months

Saturday 31st January 2015
quotequote all
sunnydude959 said:
Hi Guys.

I had a small issue with my car this morning and I was wondering if you guys could give some advice.

Basically, I started my Merc CL63 AMG (5.5 biturbo) this morning and after just driving down the road, the engine light came on. I then pulled over and rang up mercedes "MB Contact" in the phonebook (sort of like BMW assist kind of thing), and he said that it should be fine to drive to the dealership on Monday.

I then got my bluetooth diagnostic OBD adapter out, plugged it in, ran the app on my phone and it came up with the code P0300 which is engine misfire not attributed to a particular cylinder(s), apparently.

As he said it was fine to drive, I decided to wait for the engine to warm up to temperature, and then put my foot down for a short amount of time (all speed limits and laws were adhered to!). I then stopped outside a shop to get something, and when I got back in my car, the engine light had extinguished.

Is it still worth going to a Merc dealer about it? Or was it simply a blip in the system? I haven't had the light come on again since this morning.

Sunny.
What a coincidence! This is exactly what happened to the wife's car today, same circumstances. She'd driven a few hundred yards and the EML light came on along with "Reduced Performance" on the instrument binnacle. She let me know about it when she got home, sure enough I went outside to start the car up and the EML light was still on, although the "Reduced Performance" had gone out.

I left the car alone for a couple of hours before starting it back up, and everything's back to normal now. Just got back from my daughter's birthday party and the car seems fine.

Unless it happens again, I'm not particularly worried. Maybes just a slight misfire caused by a bad batch of petrol? Who knows?

Car is a 5.0 XF btw

sunnydude959

Original Poster:

907 posts

158 months

Saturday 31st January 2015
quotequote all
V88Dicky said:
What a coincidence! This is exactly what happened to the wife's car today, same circumstances. She'd driven a few hundred yards and the EML light came on along with "Reduced Performance" on the instrument binnacle. She let me know about it when she got home, sure enough I went outside to start the car up and the EML light was still on, although the "Reduced Performance" had gone out.

I left the car alone for a couple of hours before starting it back up, and everything's back to normal now. Just got back from my daughter's birthday party and the car seems fine.

Unless it happens again, I'm not particularly worried. Maybes just a slight misfire caused by a bad batch of petrol? Who knows?

Car is a 5.0 XF btw
We didn't fill up at the same petrol station did we? laugh

sunnydude959

Original Poster:

907 posts

158 months

Saturday 31st January 2015
quotequote all
xxChrisxx said:
If you can't feel it. It's not a bad misfire. id be temped to just leave it and see what happens. Unless you can get it scanned for free of course.

Random and intermittent emls are not something to worry about.

When you say service is it for oil only, or something more? If its due filters and plugs for example, that could very well fix it.
Its a "Service B" which is a major service, although i'm not too sure what it specifically includes. But yes, I agree, if they change filters and plugs, that sounds like it could get rid of the problem.

My car has done 50k miles so i'd assume it would need doing around now-ish.

V88Dicky

7,373 posts

214 months

Saturday 31st January 2015
quotequote all
sunnydude959 said:
We didn't fill up at the same petrol station did we? laugh
biggrin

I'm not going to get into the 'supermarket inferior fuel' debate, but she usually fills up at Morrisons.....

sunnydude959

Original Poster:

907 posts

158 months

Saturday 31st January 2015
quotequote all
V88Dicky said:
biggrin

I'm not going to get into the 'supermarket inferior fuel' debate, but she usually fills up at Morrisons.....
lol definitely not then! I only either fill up at Shell (Nitro+ Unleaded) or Tesco (Momentum 99) as I need 98 RON minimum for my car.

sunnydude959

Original Poster:

907 posts

158 months

Sunday 8th February 2015
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UPDATE

My car went to the dealer and advised me that they've found a faulty fuel pump, so they're going to replace it. So it wasn't a false alarm.