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Fault Code Help Please

18K views 65 replies 6 participants last post by  ronaldbroersmaw204m272 
#1 ·
2008 A209 CLK350 Convertible, about 115K miles

P0448 - Evaporative Emission System Vent Control Circuit Shorted
P2009 - Intake Manifold Runner Control Circuit Low Bank 1
P2257 - Secondary Air Injection System Control "A" Circuit Low
P0414 - Secondary Air Injection Switching Valve A Circuit Shorted
P0037 - HO2S Heater Control Circuit Low (Bank 1, Sensor 2)
P0458 - Evaporative Emission System Purge Control Valve Circuit Low
P0057 - HO2S Heater Control Circuit Low (Bank 2, Sensor 2)
P0031 - HO2S Heater Control Circuit Low (Bank 1, Sensor 1)
P0051 - HO2S Heater Control Circuit Low (Bank 2, Sensor 1)

I think there might be one or two root causes to all of the codes, e.g. the short circuits that I've italicized above.. Where do I start?

Thanks.....
 
#2 ·
I have an 06 clk350 with 89k miles. I am in the same exact situation right now as well. I have 8 out of the 9 codes that you just posted. Only one that I'm missing is the P0458. The car was fine until I got a check engine light yesterday. Any other symptoms? It seems like my radiator fan is not turning off while the engine is on. Also on a cold start I don't hear the normal whine from the secondary air pump now since the codes popped up. Have you done any repairs recently? Within the last month I've done two ignition coils, changed the spark plugs, air filters, oil change with the proper equipment, and thermostat. Hopefully we can figure this out together
 
#4 ·
Other than my wife "adjusting" the front alignment on a kerb (curb) a couple of months back, no. I think it's just old age.

The HO2S codes are for the oxygen sensors upstream and downstream of the catalyst(s). Given the age and mileage they may well be just plain worn out, or the wiring could be shorting. Until I get underneath the thing I won't know for sure. I'm hoping against hope that fixing the other faults first will correct the oxygen sensor faults.

New front oxygen sensors are $150 and up on the web (2 required), rear ones are $100 and up (or $56 and up if you buy "universal" ones you have to complete the wiring on yourself). Again, 2 are required. Just praying the catalysts aren't worn out as well. They're $650 and up. And there's two of them...
 
#5 ·
It's unlikely that all the O2 sensors would go at once. Personally, I'd get a scanner that can read MBZ-specific codes. Generic OBDII codes don't always map to the right things on these cars. Also, you can try clearing them to see what comes back.
 
#6 ·
If I can find my Autel (which got "put away somewhere", apparently), will that give me MB specific codes or do I need to go to a stealership?

Also, could the secondary air valves be causing the O2 sensor errors? E.G. by not pumping enough "secondary air" into the exhaust stream?
 
#7 ·
The Suggested fixes that I was told was that the secondary air pump and relay need to be replaced. The intake manifold needs to be replaced. O2 sensors or and electrical problem. And last but not least it needs a new ECM. All of that is major money. But it CANt be all of that. All of the codes came at once. I see it as a domino effect of one issue causing the rest of the fault codes. I haven't brought it anywhere yet. I'd like it to be a DIY before I pull the trigger and drop it off somewhere to have a professional look at it.
 
#8 ·
I'm not familiar with the Autel scanner. Best is SDS. An air pump malfunction would not trigger these specific O2 sensor errors - they are "short to ground" problems. Since it;s on all four, I'd first check the wiring, especially where all four connect right below the engine bell housing. An oil leak could get into those connections and cause problems.
 
#13 ·
Hmmmm we are getting somewhere. I checked the fuse that I replaced , #55 and guess what that one blew again. So it seems I'm on the right path. That's why the codes turned off but once it blew again it all came back. I'm going to replace the fuse again and see what happens. If it blows again I will do a further assessment to find why it keeps blowing.
 
#16 ·
Fuse 54 is for the ECU. Someone recently had this happen (here, mbworld, or maybe the W203 forums) and it was a bad coil causing it to blow. He found it by unplugging coils one at a time until the fuse did not blow.
 
#17 ·
I think you are correct. I just swapped the bank A coil because I had a code p0351 which is bank A. I swapped it with an old coilthat I saved after I replaced it with a new one on bank E. it's been 40 minutes now and the CEL has not came on. The fuse hasn't went yet either. What I did to complete this test is..... I pulled the fuse #54 out even though it was broken. Then I replaced the coil with an old one I had. Then I cleared the codes with a scanner. After I deleted the codes I then put a new fuse into bank # 54 and then started it. I took it for a drive all SEEMS well. I don't want to jump the gun and say that's it like last time. But this definitely seems to be promising. I will update tomorrow on whether or not it was completely successful.
 
#19 ·
Given the V-6 is "coil on plug", i.e. one coil per cylinder, and thus at least $240 to replace all six, is there any way to test coils before replacing them other than, say, buying one coil and swapping it out with each old coil in turn until the duff one is identified? I know it's probably wise, but is it necessary to replace all six coils at the same time?
 
#20 ·
An easy way to test for a shorted coil without spending any money (other than on fuses) is just to unplug them one at a time. You'll get misfire errors, but at least you'll find the one that blows the fuse.
 
#23 ·
I put in a new ignition coil in bank A and then I put over 60 miles of city and highway miles on today. No CEL, no blown fuses, and no pending codes either. I'm confident that the coil was the problem. Iwantedajag you also had the P0351 code so I would assume that you only need to replace the coil on bank A which is the front left coil. But if you've ordered them all already might as well swap them all. It's a very easy DIY and takes about ten minutes max to switch them all out. All you need is a T27 torx. Here's a video of a spark plug change but you can see how to remove the coil prior to doing the plugs. Just in case you are not familiar with the process. Good luck.
 
#24 ·
I am guessing an ohmmeter might give you a reading that could be interpreted as good or bad, but I don't know what this is. MBW209 has a good point - error P0351 does indicate a problem with the coil on cylinder 1, so that's a good place to start with the trial-and-error method.
 
#25 ·
Thanks guys,

If figured if one coil has gone, the others won't be far behind it, so I'm going to do all six and be done with. Maybe I'll do one at a time and see, but eventually I expect the other five to fail in short succession anyway. Hopefully it'll cure the problem. Otherwise the wife will be twisting my manly parts in the vice-grips yet again (it's her car and her $$ paying)....
 
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