C180 Kompressor coupe running rich

[Merclover2005]

Hi all, new to the forum so bare with me.

My mum's 2005 C180 kompressor coupe popped up with a check engine light the other day. I plugged my code reader in and it said "running rich" and presented code "P0172". Very confused as the car is driving and idling completely fine, no symptoms at all?! I've read that running rich can result in a strong egg smell from the exhaust and rough idle but again, I cannot smell or detect anything out of the ordinary with the car.

Note: The air intake hose was on its way out so I changed that, but it hasn't made the check engine light go off.

We are obviously in lockdown at the moment, so the car is barely being driven, I put it down to that and told her to put red ex in and fill up the car on premium fuel, to clear up the system, she did this but the check engine light remains on. She's not sure whether she should be driving it as she's worried she will damage the engine. Our usual mechanic isn't working at the moment so we cannot get it checked out by him for now. What do you guys think in regards to what may be wrong with the car and if its OK for her to drive short journeys for the time being??

Many thanks,
M.

 

[BlackC55]

They suffer badly from engine oil in the wiring loom. Lots of info on here about it. It often gets to the O2 sensors damaging them amongst other items. My best advice is to remove the plugs on them and take a look. If there is oil in the loom then its a new loom needed and maybe O2 sensors etc. Also in the past after we have replaced the loom etc a software update is required too.
Its a common issue and specialists such as myself are used to diagnosing them. There are plenty in London that can help.

 

[markjay]

Welcome to the forum.

On a very general note, the typical M271 issues are:

- Premature timing gear failure (usually fatal for the engine)

- Engine oil leaking from the camshaft position sensors at the front of the engine and going up the wiring loom (which is what BlackC55 described above). There's a modified part - loom extention - that prevents this from happening, though if it already happened then it's too late for that.

- Split vaccum hose under the air filter box (which you say you have sorted).

- Blocked engine crankcase breather (will result in EML).

- Failed coolant thermostat (luckily a quick and cheap repair on these engines).

Good luck with sorting-out your issue.

 

[Merclover2005]

Thanks for the replying and sharing advice so promptly. I wasn't aware of the oil leaking onto the O2 sensors, not sure if it was that but they may need changing anyway as the car has done over 106,000 miles now. Anyway, I started the car this morning and the EML has gone off, so it may have been due to the split hose as it was in a very bad state, although I changed it last week I've read the EML doesn't always go out straight away so it may have just taken a while. We will still get it checked out when our mechanic is back at work though as its due a service soon.

 

[markjay]

Thanks for the replying and sharing advice so promptly. I wasn't aware of the oil leaking onto the O2 sensors, not sure if it was that but they may need changing anyway as the car has done over 106,000 miles now. Anyway, I started the car this morning and the EML has gone off, so it may have been due to the split hose as it was in a very bad state, although I changed it last week I've read the EML doesn't always go out straight away so it may have just taken a while. We will still get it checked out when our mechanic is back at work though as its due a service soon.

Good news.

If you did want to peruse the modified camshaft position sensor connector to prevent the 'oil-in-loom' issue, the MB P/N is A 271 150 27 33, and you will need qty 2.

And, at that mileage, keep an eye on the timing gear!

 

[Merclover2005]

Good news.

If you did want to peruse the modified camshaft position sensor connector to prevent the 'oil-in-loom' issue, the MB P/N is A 271 150 27 33, and you will need qty 2.

And, at that mileage, keep an eye on the timing gear!

I will definately look into it as I was planning on having the car in July. In regards to the timing gear, is this inevitably going to cause me problems in the future? Are their any other common expensive repairs I should be worried about if I keep it?
My mum bought the car in 2008 and it has been very reliable, never had any major trouble. Though I understand the milage is creeping up, so I don't want to end up taking the car if it will cause me nothing but problems. I know people often say to be wary of a high milage Mercedes but I'm going to get the car for free and it's been in the family for 12 years, so I know it's history...

 

[markjay]

I will definately look into it as I was planning on having the car in July. In regards to the timing gear, is this inevitably going to cause me problems in the future? Are their any other common expensive repairs I should be worried about if I keep it?
My mum bought the car in 2008 and it has been very reliable, never had any major trouble. Though I understand the milage is creeping up, so I don't want to end up taking the car if it will cause me nothing but problems. I know people often say to be wary of a high milage Mercedes but I'm going to get the car for free and it's been in the family for 12 years, so I know it's history...

Obviously not all M271 engine go belly-up at the 100,000 miles mark. Only a small proportion do. And if the car has been regularly serviced using the correct engine oil (MB Spec Sheet 229.3/229.5) then the chances of failure are lower.

But the issue is serious enough to cause concern, even on properly-serviced cars. If this happens, there's a good chance that the car will be written-off, not to mention the potential inconvenience of finding yourself standard at the roadside. If you are lucky, you will experience rough and noisy idle, which will give you enough time to drive to a garage, or better-still to switch-off the engine and get the car towed-away to a garage, before any serious damage is done. But more often than not there is little warning.

The proper way of dealing with this by having the timing gear replaced pre-emptively. This includes the two camshaft sprocket wheels, the timing chain, tensioner and guide. The cost - parts and labour - is probably in the region of £1,200-£1,700.

The other option is to take the car to a specialist who will remove the camshaft cover and inspect the timing gear. If it's all good, you should be fine. If it isn't, then you'll need to replace the timing gear.

 

[markjay]

PS - Mercedes engines are actually quite good for very high mileage. The timing gear issue on the single-chain M271 engine is a one-off, and at any event the engine itself is good for many more miles if the timing gear is replaced in time.

 

[Merclover2005]

Aha very old thread but thought I'd update you guys of what it was. It was a vaccum hose leak on the supercharger. After a few more months of intermittent engine light warnings the car began to shudder and hiccup whenever pulling off revving or starting. Also had a faulty thermostat. So all of that got fixed last year and the car has been great since, at 116k now.

 

[W1ghty]

Aha very old thread but thought I'd update you guys of what it was. It was a vaccum hose leak on the supercharger. After a few more months of intermittent engine light warnings the car began to shudder and hiccup whenever pulling off revving or starting. Also had a faulty thermostat. So all of that got fixed last year and the car has been great since, at 116k now.

Thanks for the update buddy

 

[Jezza93]

Aha very old thread but thought I'd update you guys of what it was. It was a vaccum hose leak on the supercharger. After a few more months of intermittent engine light warnings the car began to shudder and hiccup whenever pulling off revving or starting. Also had a faulty thermostat. So all of that got fixed last year and the car has been great since, at 116k now.

Hey, thanks for the update. Just wondered how much it cost to repair the hose for the supercharger? I'm really hoping mine is the hose below the airbox but cant be certain. I've ruled out the MAF since it reads 2.4 g/s on idle and goes up accordingly when revving. Even unplugged it and it still idled like crap.

Mines giving misfires and lean codes so I'm fairly certain its a hose somewhere..

 

[Merclover2005]

Hey, thanks for the update. Just wondered how much it cost to repair the hose for the supercharger? I'm really hoping mine is the hose below the airbox but cant be certain. I've ruled out the MAF since it reads 2.4 g/s on idle and goes up accordingly when revving. Even unplugged it and it still idled like crap.

Mines giving misfires and lean codes so I'm fairly certain its a hose somewhere..

Hi, that's alright it cost me £200 and that included a new thermostat as well! I do use a very good mechanic based in London who always sorts me out for very good prices as my dad has known him for over 25 years. Not sure how much it would of cost elsewhere though! I had the same issue and it took weeks for the problem to be properly diagnosed. Had intermittent engine light and it would occasionally cough for a few seconds on start up and almost "double rev" when I revved or pulled off. All of the sudden I went up to 80 to overtake some lorries and the car started shuddering very violently and barely made it home, it was quite scary as I thought it was something worse . After this it idled like absolute crap and just wobbled whenever it was idling until it got fixed. Mine was showing a running rich code, some misfire and another code. I also had another issue with the car jerking under hardish acceleration but I had all spark plugs changed and that sorted it... What you will want to do is a smoke test to see if any of the hoses/pipes are leaking. I'm pretty sure that's what my mechanic said he did.

What model do you have exactly and what is the milage?

 

[Jezza93]

Hi, that's alright it cost me £200 and that included a new thermostat as well! I do use a very good mechanic based in London who always sorts me out for very good prices as my dad has known him for over 25 years. Not sure how much it would of cost elsewhere though! I had the same issue and it took weeks for the problem to be properly diagnosed. Had intermittent engine light and it would occasionally cough for a few seconds on start up and almost "double rev" when I revved or pulled off. All of the sudden I went up to 80 to overtake some lorries and the car started shuddering very violently and barely made it home, it was quite scary as I thought it was something worse . After this it idled like absolute crap and just wobbled whenever it was idling until it got fixed. Mine was showing a running rich code, some misfire and another code. I also had another issue with the car jerking under hardish acceleration but I had all spark plugs changed and that sorted it... What you will want to do is a smoke test to see if any of the hoses/pipes are leaking. I'm pretty sure that's what my mechanic said he did.

What model do you have exactly and what is the milage?

Cheers! Lets see what my mechanic says about it. Its exactly the same as yours, C180 Kompressor, 110K miles, FSH although its due one atm. The issues you describe sounds exactly like mine, I tried to get up close to listen for any leaks but cant hear anything at all mainly due to a VERY squeaky belt/pulley..

 

[Continental]

Hi all, new to the forum so bare with me.

My mum's 2005 C180 kompressor coupe popped up with a check engine light the other day. I plugged my code reader in and it said "running rich" and presented code "P0172". Very confused as the car is driving and idling completely fine, no symptoms at all?! I've read that running rich can result in a strong egg smell from the exhaust and rough idle but again, I cannot smell or detect anything out of the ordinary with the car.

Note: The air intake hose was on its way out so I changed that, but it hasn't made the check engine light go off.

We are obviously in lockdown at the moment, so the car is barely being driven, I put it down to that and told her to put red ex in and fill up the car on premium fuel, to clear up the system, she did this but the check engine light remains on. She's not sure whether she should be driving it as she's worried she will damage the engine. Our usual mechanic isn't working at the moment so we cannot get it checked out by him for now. What do you guys think in regards to what may be wrong with the car and if its OK for her to drive short journeys for the time being??

Many thanks,
M.

When you say air intake hose - which hose are you referring to?
Did you replace the vacuum hose underneath the air filter housing box?
Basically what the guy is talking about in this video -

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edit ignore I think you’ve done this as you say the EML took a while to go out, but it has gone out now it seems. Would also say as I think others have mentioned to get the cam shaft magnet sensors checked out.

 

[Merclover2005]

Cheers! Lets see what my mechanic says about it. Its exactly the same as yours, C180 Kompressor, 110K miles, FSH although its due one atm. The issues you describe sounds exactly like mine, I tried to get up close to listen for any leaks but cant hear anything at all mainly due to a VERY squeaky belt/pulley..

Yeah just see what they say it will most likely be one of the . Ah I see, I was going to say this issue usually occurs not long after 100k miles.. So it would make sense if your car does have this issue especailly if you're experiencing the same issues as I had. I couldn't really hear any leaks at the time either but then again I didn't really know what I was looking for.

 

[Jezza93]

Yeah just see what they say it will most likely be one of the . Ah I see, I was going to say this issue usually occurs not long after 100k miles.. So it would make sense if your car does have this issue especailly if you're experiencing the same issues as I had. I couldn't really hear any leaks at the time either but then again I didn't really know what I was looking for.

Definitely hope its that issue, seems to be an easy enough fix for any mechanic. Just out of curiosity, where is your mechanic based? If he's close to me, I might just give him a visit.

 

[Merclover2005]

When you say air intake hose - which hose are you referring to?
Did you replace the vacuum hose underneath the air filter housing box?
Basically what the guy is talking about in this video -

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For more detailed information, see our cookies page.

Accept third party cookies

edit ignore I think you’ve done this as you say the EML took a while to go out, but it has gone out now it seems. Would also say as I think others have mentioned to get the cam shaft magnet sensors checked out.

I basically meant the large fabric looking hose at he front of the engine bay that connects to the s/c. But not the ones where the intake manifold is or the one underneath the air box. I'm assuming they were the hoses that my mechanic repaired when he fixed the car. The car was fixed in October 2020 and been fine since no eml or anything.

 

[Merclover2005]

Definitely hope its that issue, seems to be an easy enough fix for any mechanic. Just out of curiosity, where is your mechanic based? If he's close to me, I might just give him a visit.

He's located in Lewisham. The garage he works at is called 'Nathan's Autos'. It's a BMW specialist garage but Frank, my mechanic works on any car. He has been working on ours since 2008 when we got the coupe so is very familiar with those cars.

 

[Merclover2005]

Definitely hope its that issue, seems to be an easy enough fix for any mechanic. Just out of curiosity, where is your mechanic based? If he's close to me, I might just give him a visit.

Although he is going on holiday this week so if you need the car fixed ASAP then you may be better off taking it somewhere else but you can always enquire..

 

[Jezza93]

He's located in Lewisham. The garage he works at is called 'Nathan's Autos'. It's a BMW specialist garage but Frank, my mechanic works on any car. He has been working on ours since 2008 when we got the coupe so is very familiar with those cars.

Brilliant, I used to live in Catford so I'm pretty familiar with the area. Thanks for the tips!