Replaced Hose, Still CEL, probably O2 sensor
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Replaced Hose, Still CEL, probably O2 sensor
This is regarding a 2003 coupe with the m271 engine. One day the CEL came on and the the following codes:
P0138
P0170
P0178
I took it to the shop and they replaced the crankshaft hose which was visibly torn. However, after a day, the CEL came on again, this time throwing the following codes:
P0136
P0138
Those two codes above have to do with the second O2 sensor. Today, I read those codes and reset/deleted them. I then drove 3 miles and the CEL has yet to come on. The engine does feel "different" so I'm pretty sure it will come on again. What do you think, second O2 sensor?
Is there a tutorial than the one in the DIY sticky (https://mbworld.org/forums/c-class-w...acement.html)? The guy seems like an idiot. Do I really need a jack stand to get to the second O2 sensor? I might have to take it to the shop again.
Thanks for your help.
P0138
P0170
P0178
I took it to the shop and they replaced the crankshaft hose which was visibly torn. However, after a day, the CEL came on again, this time throwing the following codes:
P0136
P0138
Those two codes above have to do with the second O2 sensor. Today, I read those codes and reset/deleted them. I then drove 3 miles and the CEL has yet to come on. The engine does feel "different" so I'm pretty sure it will come on again. What do you think, second O2 sensor?
Is there a tutorial than the one in the DIY sticky (https://mbworld.org/forums/c-class-w...acement.html)? The guy seems like an idiot. Do I really need a jack stand to get to the second O2 sensor? I might have to take it to the shop again.
Thanks for your help.
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
The second sensor requires you to remove the skid plate from under the car. Please do yourself a favour and check the camshaft sensor connections for the dreaded oil leaks & make sure that oil has not got into the wiring harness and contaminated your O2 sensors. I'm not going to repeat it all. Look at the DIY sticky and search the forum. We have covered this issue many, many times. If your car does not have the cam sensor pigtales fitted, then fit them soonest. If the cam sensors are leaking then replace them & clean or replace the harness. You must check the second O2 sensor for oil - good luck 
BTW what mileage has the vehicle done? I hope for your sake it's just a failed O2 sensor.
BTW what mileage has the vehicle done? I hope for your sake it's just a failed O2 sensor.
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cl203 Sports Coupe
I actually had this problem on my coupe too....and my technician told me it was the K&N filter that I had installed...we changed the filter back to an OEM filter and walaaa no more CEL...came to a conclusion that the K&N filters are extremely hard to maintain so i pretty much gave up on having that installed...iono this might be your problem too? good luck!
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
The more I read your situation, the more I think you have leaking cam sensors. Let us know what you find.
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C230K
I just drove to the store and back (1 mile each way) and the CEL did not come back on.
More on my situation:
Both times the CEL came on, I was on the highway. Could it be a heat or stress problem.
A more technical question:
When the CEL comes on the engine "appears" to on an open loop mode, but when I reset the code with an OBDII computer, the car seems to go back into closed loop operation. Will the car ever go back to closed loop if there are stored codes (the CEL light being on).
Thanks.
Last edited by dead_eye; Jan 27, 2009 at 07:17 PM. Reason: typo
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C230K
I actually had this problem on my coupe too....and my technician told me it was the K&N filter that I had installed...we changed the filter back to an OEM filter and walaaa no more CEL...came to a conclusion that the K&N filters are extremely hard to maintain so i pretty much gave up on having that installed...iono this might be your problem too? good luck!
Thanks.
Last edited by dead_eye; Jan 27, 2009 at 07:23 PM. Reason: clarity
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
Yeah I thought the same too. In fact I pointed it out to the mechanic when I brought it to the shop. The CAM sensors were bone dry. Plus he said he seen the CAM problem before and that you should be able to see oil. Do you think the CAM sensors might've leaked some time in the past? Sensors sometimes just go bad, so if the problem continues, hopefully it's just that.
I just drove to the store and back (1 mile each way) and the CEL did not come back on.
More on my situation:
Both times the CEL came on, I was on the highway. Could it be a heat or stress problem.
A more technical question:
When the CEL comes on the engine "appears" to on an open loop mode, but when I reset the code with an OBDII computer, the car seems to go back into closed loop operation. Will the car ever go back to closed loop if there are stored codes (the CEL light being on).
Thanks.
I just drove to the store and back (1 mile each way) and the CEL did not come back on.
More on my situation:
Both times the CEL came on, I was on the highway. Could it be a heat or stress problem.
A more technical question:
When the CEL comes on the engine "appears" to on an open loop mode, but when I reset the code with an OBDII computer, the car seems to go back into closed loop operation. Will the car ever go back to closed loop if there are stored codes (the CEL light being on).
Thanks.
I'm delighted that you don't have leaking cam sensors. Please fit the pigtales so when they leak you don't compromise anything.
Last edited by Glyn M Ruck; Jan 28, 2009 at 03:54 AM.
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C230K
Are you sure. I thought every modern car goes into open loop when one of the emissions sensors (o2, maf) fail?
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
You have me interested now - I don't know - let me do some scratching. We might have a definition problem here. I thought that it went onto a default map if a sensor failed or gave what Benz call implausible output.
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
Yes, by definition we are both correct. Aside from WOT the vehicle will go into open loop & run on a default map if it receives implausible feed from some sensors. Nobody can tell me which but I'm sure MAF would be one and O2 another. Cancelling things will put it back into closed loop until another code of the correct nature is thrown in which case it goes open loop again & onto a default map.
Default map does not mean poor running - just not optimum running & emissions
So it depends what triggers the CEL as to whether it goes open loop or not with the CEL burning.
Default map does not mean poor running - just not optimum running & emissions
So it depends what triggers the CEL as to whether it goes open loop or not with the CEL burning.
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C230K
My CEL came on again at roughly the same place at my daily commute where it usually fails. I had to drive around a bit for work and it didn't come on so I was illogically hoping I was in the clear. This time i only got the P0136 code. I'm thinking that the downstream O2 sensor actually went bad.
Any opinions?
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
No I'm an oil industry technical person of 37 years just retired but still consulting - see my profile.
I'm afraid it looks like you need a new lambda sensor
I'm afraid it looks like you need a new lambda sensor
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C230K
It's too bad that it'll have to go to the shop again as I don't feel comfortable jacking up the car. Is the mercedes O2 sensor the same as the Bosch sensor that your average auto parts store would sell.
for example: http://www.autozone.com/selectedZip,.../selectZip.htm (i like how the price jumped up 20 dollars when i typed in 90210 for the zip code)
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
Replacing the sensor is not hard. But you must decide for yourself what you are prepared to do for safety reasons et al.
Bosch make universal sensors & the Merc genuine article which I understand to be preheated.
That Autozone sensor looks correct - the generics are cheaper - I guess the Beverley Hills code brings in CA tax or maybe just rich beeotch tax
Stay out of the oilco downstream - It's a dynosaur industry run by dynosaurs. I had a wonderful global career but today it sucks. I'm pleased to be out & not so pleased to be consulting due to the brain drain the industry has suffered due to their own stupidity. Today they hire people that are PC not competent.
Bosch make universal sensors & the Merc genuine article which I understand to be preheated.
That Autozone sensor looks correct - the generics are cheaper - I guess the Beverley Hills code brings in CA tax or maybe just rich beeotch tax
Stay out of the oilco downstream - It's a dynosaur industry run by dynosaurs. I had a wonderful global career but today it sucks. I'm pleased to be out & not so pleased to be consulting due to the brain drain the industry has suffered due to their own stupidity. Today they hire people that are PC not competent.
Last edited by Glyn M Ruck; Jan 29, 2009 at 02:56 AM.
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C230K
Thanks for your help. It turned out to be leaking CAM sensors, at least at one point. Even though they were bone dry when I looked at them (last ~5k miles) there was oil in the CAM sensor. Unfortunately, my mechanic caught the flu and get to it until the next week. Luckily I have access to another car so I can wait.
People that had m271 CAM sensor problems:
Is that usually the end of it? Did they make any changes to the leaking gasket such as changing its material to silicone? I understand that the ECU could go bad (but it's still covered under the 80k emissions warranty so no problems) and the other sensors (o2 upstream and MAF) could fail due to previous oil exposure, but I'm prepared to shell out for those. My main concern is if the CAM sensors will leak again.
People that had m271 CAM sensor problems:
Is that usually the end of it? Did they make any changes to the leaking gasket such as changing its material to silicone? I understand that the ECU could go bad (but it's still covered under the 80k emissions warranty so no problems) and the other sensors (o2 upstream and MAF) could fail due to previous oil exposure, but I'm prepared to shell out for those. My main concern is if the CAM sensors will leak again.
Replacing the sensor is not hard. But you must decide for yourself what you are prepared to do for safety reasons et al.
Bosch make universal sensors & the Merc genuine article which I understand to be preheated.
That Autozone sensor looks correct - the generics are cheaper - I guess the Beverley Hills code brings in CA tax or maybe just rich beeotch tax
Stay out of the oilco downstream - It's a dynosaur industry run by dynosaurs. I had a wonderful global career but today it sucks. I'm pleased to be out & not so pleased to be consulting due to the brain drain the industry has suffered due to their own stupidity. Today they hire people that are PC not competent.
Bosch make universal sensors & the Merc genuine article which I understand to be preheated.
That Autozone sensor looks correct - the generics are cheaper - I guess the Beverley Hills code brings in CA tax or maybe just rich beeotch tax
Stay out of the oilco downstream - It's a dynosaur industry run by dynosaurs. I had a wonderful global career but today it sucks. I'm pleased to be out & not so pleased to be consulting due to the brain drain the industry has suffered due to their own stupidity. Today they hire people that are PC not competent.
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300E a couple 1994 w124wagon E320 Wagon/,1971MGB Track/Rally, MG Midget Autocross ,2000 E320 wagon.
Why
don't you install your own cam sensor and maf and o2 sensors?
Less than $600 for all the parts and a sat. morning working on the car.
Clearing a check engine light does not remove the problem or improve performance when something is wrong.It just clears the light,the code remains stored in the ecu and the condition remains active.
The indie is going to break your wallet if you keep going to him.Do you have your own obd2 scanner?They are only $45 for one that will read,clear and display I/M readiness codes.
Less than $600 for all the parts and a sat. morning working on the car.
Clearing a check engine light does not remove the problem or improve performance when something is wrong.It just clears the light,the code remains stored in the ecu and the condition remains active.
The indie is going to break your wallet if you keep going to him.Do you have your own obd2 scanner?They are only $45 for one that will read,clear and display I/M readiness codes.
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C230K
I think you're missing some of what's on the thread. I only went to the indie once. I cleared the codes for free at autozone. The indie needs to repair the cam sensors and downstream o2 sensor. I really can't do the downstream because I'm not comfortable with a jack, so it's worth it.
As for the upstream and MAF, apparently they're easy to do with just hood access, so I'll probably do them myself, but they're not failing according to the codes.
Where I'm at now is if the new CAM sensors (and new isolating wires) are a good fix?
Thanks.
As for the upstream and MAF, apparently they're easy to do with just hood access, so I'll probably do them myself, but they're not failing according to the codes.
Where I'm at now is if the new CAM sensors (and new isolating wires) are a good fix?
Thanks.
don't you install your own cam sensor and maf and o2 sensors?
Less than $600 for all the parts and a sat. morning working on the car.
Clearing a check engine light does not remove the problem or improve performance when something is wrong.It just clears the light,the code remains stored in the ecu and the condition remains active.
The indie is going to break your wallet if you keep going to him.Do you have your own obd2 scanner?They are only $45 for one that will read,clear and display I/M readiness codes.
Less than $600 for all the parts and a sat. morning working on the car.
Clearing a check engine light does not remove the problem or improve performance when something is wrong.It just clears the light,the code remains stored in the ecu and the condition remains active.
The indie is going to break your wallet if you keep going to him.Do you have your own obd2 scanner?They are only $45 for one that will read,clear and display I/M readiness codes.
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
Thanks for your help. It turned out to be leaking CAM sensors, at least at one point. Even though they were bone dry when I looked at them (last ~5k miles) there was oil in the CAM sensor. Unfortunately, my mechanic caught the flu and get to it until the next week. Luckily I have access to another car so I can wait.
People that had m271 CAM sensor problems:
Is that usually the end of it? Did they make any changes to the leaking gasket such as changing its material to silicone? I understand that the ECU could go bad (but it's still covered under the 80k emissions warranty so no problems) and the other sensors (o2 upstream and MAF) could fail due to previous oil exposure, but I'm prepared to shell out for those. My main concern is if the CAM sensors will leak again.
People that had m271 CAM sensor problems:
Is that usually the end of it? Did they make any changes to the leaking gasket such as changing its material to silicone? I understand that the ECU could go bad (but it's still covered under the 80k emissions warranty so no problems) and the other sensors (o2 upstream and MAF) could fail due to previous oil exposure, but I'm prepared to shell out for those. My main concern is if the CAM sensors will leak again.
Last edited by Glyn M Ruck; Feb 8, 2009 at 06:22 AM. Reason: pic trouble
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2019 GT3 RS, 2017 M3 30 Jahre
Glyn, thanks for posting the pics. Are the isolation wires difficult to put on? I assume that I take out the wires from the Cam sensors, plug them into the isolation wires and then plug the isolation wires into the Cam sensors right? (Oh and zip-tie them together.)
I'm having a similar problem to Dead_Eye and I hope that it's not as severe: https://mbworld.org/forums/c-class-w...-cold-cel.html
I'm having a similar problem to Dead_Eye and I hope that it's not as severe: https://mbworld.org/forums/c-class-w...-cold-cel.html
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
Phil - dead simple and as you describe - Just make sure to zip tie them securely out of the way of the Poly V belt.
Another solution
Another solution
