CEL after plug change
Thread Starter
Junior Member
Joined: Sep 2008
Posts: 31
Likes: 0
2006 c280
CEL after plug change
Hi guys.
Just wanted to start by saying thanks for the valuable information you guys provide. I've been able to do a lot of work on my car myself, and in the least, I walked into the dealership knowing enough to not get screwed.
Following the DIY posted here, I decided to change all the spark plugs on my '06 c280. I had a slight shudder at idle and the engine seemed a bit anemic, so at nearly 60k miles, I knew I was probably ahead of schedule but decided to do the change anyway. I intend to post pics of the old plugs next week, but to my untrained eyes, they looked okay if not a little worn down.
Regardless, the plug swap went smoothly, but 48 hours after doing it, I got a CEL. Not having a stealership nearby, I stopped by the local autozone and had the codes pulled. He didn't give me the exact code, but said "the oxygen sensor was defective or shorting out". I'm taking it to the dealership next week (still under warranty).
What are the chances that I caused this doing the plug change? Is it (one helluva) coincidence? I used the OEM bosch platinum plugs, no dialectric, plugs were pre-gapped, used a torque wrench (plugs said 20 nm on them). Can't imagine what I did wrong....
Thanks
Just wanted to start by saying thanks for the valuable information you guys provide. I've been able to do a lot of work on my car myself, and in the least, I walked into the dealership knowing enough to not get screwed.
Following the DIY posted here, I decided to change all the spark plugs on my '06 c280. I had a slight shudder at idle and the engine seemed a bit anemic, so at nearly 60k miles, I knew I was probably ahead of schedule but decided to do the change anyway. I intend to post pics of the old plugs next week, but to my untrained eyes, they looked okay if not a little worn down.
Regardless, the plug swap went smoothly, but 48 hours after doing it, I got a CEL. Not having a stealership nearby, I stopped by the local autozone and had the codes pulled. He didn't give me the exact code, but said "the oxygen sensor was defective or shorting out". I'm taking it to the dealership next week (still under warranty).
What are the chances that I caused this doing the plug change? Is it (one helluva) coincidence? I used the OEM bosch platinum plugs, no dialectric, plugs were pre-gapped, used a torque wrench (plugs said 20 nm on them). Can't imagine what I did wrong....
Thanks
Senior Member
Joined: Jan 2010
Posts: 283
Likes: 2
From: Mississauga, Ont.
2007 C280 4matic Avantgarde
First of all I would buy OBD2 Scanner since it’s cheap and can give you a hand in future. As Glyn says they are unrelated and I recommend you to check air filter box. Happened to me twice when I was putting it back. You probably have air leak in throttle body because seal from air filter box not sitting properly on seal at throttle body. It’s kind of hard to notice but you can see if they are misaligned if you look at aluminum square kind of grill at top of the engine and square hole in air filter box. Should look as in picture below. Gap should be same all around.
Last edited by ontmiss; Aug 19, 2010 at 10:15 PM.
Thread Starter
Junior Member
Joined: Sep 2008
Posts: 31
Likes: 0
2006 c280
thanks guys.
I actually went to autozone intending to buy an OBDII, but when I asked them to pull the codes for me their device was unable to read the code. The same thing then happened at another autozone and an o'reilly. Each time, the code reader was confirming communication between device and car, but the code could not be read. Tried it with the car on (but not cranked) and with the car cranked. As a result, I was hesitant to buy a reader myself, fearing that there was a strong chance it would not work anyway. A friend at a local mechanic was finally able to read it with one of the more-expensive scanners.
As for the misaligned engine cover... I, unfortunately, learned this the hard way. Months ago, after replacing the air filters, I took my car to the dealership because the CEL came on. I was, politely, told that it was because I failed to put the airbox back on properly. How embarassing! Either way, isn't that a different code than the "faulty or short-circuiting oxygen sensor" error that I got?
I actually went to autozone intending to buy an OBDII, but when I asked them to pull the codes for me their device was unable to read the code. The same thing then happened at another autozone and an o'reilly. Each time, the code reader was confirming communication between device and car, but the code could not be read. Tried it with the car on (but not cranked) and with the car cranked. As a result, I was hesitant to buy a reader myself, fearing that there was a strong chance it would not work anyway. A friend at a local mechanic was finally able to read it with one of the more-expensive scanners.
As for the misaligned engine cover... I, unfortunately, learned this the hard way. Months ago, after replacing the air filters, I took my car to the dealership because the CEL came on. I was, politely, told that it was because I failed to put the airbox back on properly. How embarassing! Either way, isn't that a different code than the "faulty or short-circuiting oxygen sensor" error that I got?
