[Mercedes] 2001 MB C240 - Check Engine Codes Mystery!

[Rich Benzer]

Spend $150 on a Launch or iCarsoft scanner and you can do it all yourself easily.  Saves so much time and aggravation to be able to do it yourself whenever you need to do it

—R.B

> On Mar 11, 2026, at 6:42 PM, Robert Koziak via Mercedes <mercedes at okiebenz.com> wrote:
> 
> Hi Dan,
> 
>     That gives me a clearer picture.  I will have the car checked out with a live scan and report back.
> 
> Thanks,
> Bob
> 
> On Wednesday, March 11, 2026 at 05:45:29 PM EDT, dan penoff.com via Mercedes <mercedes at okiebenz.com> wrote:
> 
> 
> Bob,
> 
> As a reference, there are “persistent” faults and “current” faults that can trigger a CEL. In most cases, the fault has to occur a certain number of times (or more) in a given period of time - if you get a miss, say 10 times in 60 seconds, that might be the threshold that triggers a CEL.
> 
> With a real-time scanner you can see what’s happening at each cylinder, and potentially intermittent faults that, over time, are triggering your CEL.
> 
> Don’t throw parts at it based on codes - gather as much information as you can and then decide how you want to approach the repair.
> 
> -D
> 
>> On Mar 11, 2026, at 1:44 PM, Robert Koziak via Mercedes <mercedes at okiebenz.com> wrote:
>> 
>> HF,
>> I only read and clear the codes with my scanner.  I would have to go to a mechanic with a profession scanner for real time data.  
>> 
>> Since the car is running fine now with no codes would a real time scanner still be able to diagnose an issue?  I don't like throwing parts at the car but figured it might be time to replace the original plugs and coil packs until I saw that post with my exact problem except it never corrected itself like mine.
>> Thanks
>> Bob
>> 
>> On Wednesday, March 11, 2026 at 04:13:09 PM EDT, Buggered Benzmail via Mercedes <mercedes at okiebenz.com> wrote:
>> 
>> 
>> What do those codes mean on your car?  Do you have a scanner that can see real time data from the ECU?  You can see all kinds of useful parameters to help diagnose the problems rather than throwing parts at it
>> 
>> --HF
>> Sent from iFōn
>> 
>>> On Mar 11, 2026, at 3:07 PM, Robert Koziak via Mercedes <mercedes at okiebenz.com> wrote:
>>> 
>>> 
>>>    Hi All,
>>> 
>>>         My MB 2001 C240 w/130K (while accelerating) suddenly started to sputter with a flashing check engine light and stalled.   This happened two more times before the car started to run fine with a steady check engine light.  I drove home and checked the codes with the following codes: P0300, P0301, P0302 & P0303.  I figured I would change all the plugs (12!) and coil packs until I saw the following past post from another Mercedes Forum:
>>> 
>>> Post:
>>> ok guys... my buddy was driving his 02 c240 and all of the sudden it lost power and semmed to be riding on half the amount of cylinders and the check engine light came on and started flashing. we checked the codes and it threw 8 codes initially. it was P0300, P0301, P0302, P0303 and it repeated for tha last four codes. i had changed the wires and all 12 plugs (i also swapped all coils from cyls 1-3 to 4-6) and cleared the codes. There was no change except the codes went from 8 to 4 codes (still the same). The problem did not move and the car still sounds and feels like its running on 3 cyls and if i press the accelerator, it will go close to 3k rpm and begin to drop as if its dying (this is with my foot stillon the pedal). i then cleared the code and disconnected the MAF, put the key in and started the car... it still sounded and felt like sh.. but when i accelerate it will go beyond 3k rpm. any ideas? i could really use them. 
>>> 
>>> 
>>> Any ideas before I spend $400.00 for replacement plugs and coil packs.  The problem seems to be isolated to Bank 1 (#1, #2 and #3 cylinders).  The hesitation and sputtering happened 6 months ago but was a short duration with no codes?  The car has been running fine for the past 150 miles with no check engine light?
>>> 
>>> As always thanks in advance!
>>> 
>>> Bob K
>>> 
>>> -- 
>>> 
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