Sadly it is not nonsense. Granted a lot of engines are multivalve variable timing engines but sadly Mercedes is not the company it once was where it made cars of quality to last. These engines do have a design defect recognised by Mercedes but kept quite about. They fixed it on later engines. I think it affected a couple of years 02/03 but I may be wrong on exact date. Symptoms are misfire evident at tick over. Engine ECU throws up no codes except misfire normally 1 and / or 4. My experience and advice is as follows if this does happen to you then do the basics first , check the obvious things as it could be these:-

1) Check change plugs, coil packs - Mo a could pack and see if fault moves if it does your lucky one as these are relatively cheap to change

2) Check Cam sensor for oil ingress into wiring. If you have this then can cause electrical issues

3) Check breather pipe for hole. Not easy to access it is under airbox but normally if this has a hole in you also get codes thrown up indicating a fuel mixture issue. These dow go over time.

4) Undertake a compression test. If # 1 most likely or any cyclinder is down then standby for an expensive shock as you will be having head changed.

If having completed the above and 4) is indicating a compression difference and you can find no other cause then don't waste any time and money fitting parts you don't need. Solution:

1) You may be lucky. MB recognising the problem upgraded the ECU software to provide an engine burn feature. essentially running the engine to a very hot temperature to try to burn off any deposits. It may work and worth a try but may not if exhaust valves knackered. Cost is about £100 ish

2) Invest time finding someone competent and reasonable to change cylinder head. Ouch ! I looked into doing this myself but this engine is complicated and there are a number of critical alignments. You need some specialist tools. Find a good mechanic familiar with mercs and raid the piggy bank.

Lesson I learned is that it confirmed my belief that now having had BMW, Porsche and now Mercs that the believe that German engineering is reliable is a total myth. These cars are no more reliable than a Ford in some cases significantly less. Give me Japanese car any day if you want reliability. I have had a number of japanese cars and the reilability is significantly better. Not as stylist but if you want to get from A to B a better choice.

Hope this helps anyone with this problem. If Mercedes was truly quality focused then they would put this right FOC on all cars up to 100k but there not and they earn good money from people having to pay £3k having a head changed. There are independents who will do repair for £1.5k-2k

That said appart from this expensive issue the car has been good but this has certainly made me think twice.

My car has now a new head and is running smoothly with no misfire problem

Good luck. Hope this helps anyone with this issue it took me time and a lot of money to work out was was the enderlying cause. I hope this can help someone.

Update on my issue. Sadly it appears it is not nonsense. Granted a lot of engines are multivalve variable timing engines but sadly Mercedes is not the company it once was where it made cars of quality to last. These engines do have a design defect recognised by Mercedes but kept quite about. They fixed it on later engines. I think it affected a couple of years 02/03 but I may be wrong on exact date. Symptoms are misfire evident at tick over. Engine ECU throws up no codes except misfire normally 1 and / or 4. This is a good indicator to what issue maybe. My experience and advice is as follows if this does happen to you then do the basics first , check the obvious things as it could be these:-

1) Check change plugs, coil packs - Mo a could pack and see if fault moves if it does your lucky one as these are relatively cheap to change

2) Check Cam sensor for oil ingress into wiring. If you have this then can cause electrical issues

3) Check breather pipe for hole. Not easy to access it is under airbox but normally if this has a hole in you also get codes thrown up indicating a fuel mixture issue. These do go over time.

4) Undertake a compression test. If # 1 most likely or any cyclinder is down then standby for an expensive shock as you will be having head changed. Second big indicator of valve issue

If having completed the above and 4) is indicating a compression difference and you can find no other cause then don't waste any time and money fitting parts you don't need. Solution:

1) You may be lucky. MB recognising the problem upgraded the ECU software to provide an engine burn feature. essentially running the engine to a very hot temperature to try to burn off any deposits. It may work and worth a try but may not if exhaust valves knackered. Cost is about £100 ish Did not work for me although some modest improvement in general running but misfire still evident

2) Invest time finding someone competent and reasonable to change cylinder head. Ouch ! I looked into doing this myself but this engine is complicated and there are a number of critical alignments. You need some specialist tools. Find a good mechanic familiar with mercs and raid the piggy bank.

Lesson I learned is that it confirmed my belief that now having had BMW, Porsche and now Mercs that the belief that German engineering is reliable is a total myth. These cars are no more reliable than a Ford in most cases significantly less. Give me Japanese car any day if you want reliability. I have had a number of japanese cars and the reilability is significantly better. Not as stylish but if you want to get from A to B on low running costs a much better choice.

Hope this helps anyone with this problem. If Mercedes was truly quality focused then they would put these issues right FOC on all cars up to 100k but, there not and they earn good money from people having to pay £3k having a head changed. There are independents who will do repair for £1.5k-2k

That said apart from this expensive issue the car has been otherwise good but this has certainly made me think twice.

My car has now a new head and is running smoothly with no misfire problem

Good luck. Hope this helps anyone with this issue it took me time and a lot of money to work out was was the enderlying cause. I hope this can help someone.