Brian_I.

I just got my used '99 CLK 320 two weeks ago and the Check Engine light has been on since day 2. The only thing I can remember doing was adding some of that fuel injector cleaner/additive to the gas when I filled up on day 1. Since then I took it back to the dealership about 6 times and they can't tell me what the problem is. They keep wanting more time to work on it but since I just got the damn thing I just can't see myself parting with it for more than a day. So I have been just trying to "ride it out" and hope nothing happens since the performance has not diminished one bit.

Now, for the last 3 days the check engine light decided that it didn't want to come on any more and I have been so excited about that. It has been such a relief not to have that thing shining in my face everytime I go for a spin. But wait, this afternoon I go to lunch with my friends and I have the A/C on blast since it finally hit the high 70's here in Downtown LA and what do you know, the damn light comes on. One of my friends said the temperature seemed high but wasn't sure of the norm for Benz'. It was reading about 95C when we were on our way back to the office.

Do you all think the radiator might be going out or something? What's the normal temperature reading supposed to be? Does adding cleaning additives really damage the engine as the manual warns? Does anyone else have these kinds of problems or am I the only lucky one?

Sorry for the long drawn out post but I wanted to let you guys know as much history as I can put out there. Thanks in advance for any input.

jnjrowland

Regarding the temp for the engine - I have an '02 CLK320 and it can run into the 90-100 range at times. It has been this way since new and others here have confirmed that this is not unusual.

Re: the check engine light. I have to ask if your fuel cap is sealed tight and that you did not fuel up with the engine running. I know this may be obvious but the check engine light will come on if there is a problem with the cap being loose or off with the engine running.

Good luck and I'm sure you'll get this resolved.

JR

Mach430

They can't tell you what code is setting off the check engine light?

Brian_I.

I definitely checked the fuel tank cap and am pretty sure it's on tight. I also didn't fill up with the engine on.

The guy at the stealership just tells me that "they can't seem to find any problem". If there's no problem, then why does the light keep coming on?

I am going to buy one of those OBDII testers at Kragen tomorrow and hopefully it will give me a code so that at least I can tell what might be causing it for my own curiosity.

I just want to get the damn light off, even if it means taking it to an outside MB mechanic since I have had it with the service dept. at the dealership.

Thanks for the input, I will post up the error code tomorrow and ask you guys what your thoughts are on the problem.

lionj

hope everything works out ok, do keep us posted.

Mach430

Call your service rep and have him tell you the error code. Then go to www.obdii.com/codes and look it up. Or post it here, and I will see if I can help over the web.

It is disgusting that the dealer is giving up so quickly when you had it for 2 days!

Ahmed

thats sick!

byip25

sh@# , it must be fate because my car has been having the same problem. come to the forum and see this thread. my car's check engine light has been coming on after i get gas. i know that it has something to do with the gas cap. every time thats its come on i get out and fuss with the cap and re tighten the damn thing and the light has turned off. HOWEVER, the light does not turn off right away. it usually takes another day or two. but i was just about to make an apt w/ the stealer ship to see if they can fuss with it and see this thread. i guess i will wait until it stays on for more than a week before taking it in. my suggestion, try fussing with the gas cap and see what happens.

b

mmgrad

thats never happened to me before, but on our c320, the light came on (car was about 2 months old) after getting gas cause the cap wasn't tight... my advisor and others said that it will take a while for the light to turn off... that it will require a few starts to have the sensor re-read and determine that the cap is tight

Brian_I.

Alright, I went and bought an OBDII code reader and here are the codes and errors that came up:

P0141 Generic O2 Heater Circuit (Bank 1, Sensor 2)
P0136 Generic O2 Circuit (Bank 1, Sensor 2)
P0150 Generic O2 Circuit (Bank 2, Sensor 1)

Has anyone had their O2 sensors replaced? If so, do you have any idea on how much that costs? I am debating whether I should just take it to my mechanic and just pay him and get it fixed right away or go to the dealership and have it fixed under warranty but have to go through all the other bullshiznit they put you through.

nickm

I saw the check engine light come on and I thought it was the gas cap. I tightened it and started shutting off the engine when I was putting gas and then it went away. But then it came back. And on and off...
90% of the times when it does that, it is a faulty O2 sensor. Eventually after about a month, the Check Engine light will stay on until you replace the faulty sensor. Since I believe it's only an emissions sensor, you can delay taking it to the mechanic (can someone confirm this? Thanx).

Brian_I.

I was reading that the O2 sensors are what regulate the air/fuel mixture and if that is not working then your gas mileage may decrease as well as overall vehicle performance. I also read that if left "untreated" the problem could grow and possibly damage the catalytic converter, which will be even more costly to fix. I am far from a mechanic and don't know much about cars so if this info is incorrect pls correct me.

byip25

dont know if it helps. when i took my clk in this past weekend for an oil change, i told the service advisor about the check engine light/gas cap problem. he said to check it out would cost $95 already. a much cheaper 1st try would be to purchase a replacement cap and see if the cap can correct the problem. he said that sometimes the caps dont seal the pressure valve tightly after time and that would be the cheapest way to correct it. its worth a try to me so if this becomes a chronic problem i may try it... hope that helps!

b

Brian_I.

I finally got the dealership to replace all four O2 sensors and the MIL light has gone off permanently (crossing fingers). Thanks for everyone's input on this.

FYI, just to change out the two post-catalyst sensors would have costed me $365, so I am glad I didn't have to pay for it.

Supermeals

Mine goes on and off all the time too....but I just ignore it now. Sometimes on, somtimes off - I am pretty sure (99%) its the gas cap. When I eventually take it in for service, I will let you know what they say. I will have to say this - for as much money as these things costs, they seem to have a lot of issues!

SoCalCLK

Drop it off at the dealer first, try and get a loaner car or something, and have them replace the O2 sensor and anything else. If it still gives you trouble, complain to 1-800-mercedes and take it to an independent mechanic. Good luck!

Jonny

I have the same problem whit my car. (CLK 320 -00)
But my check engine light comes on when the car has ben standig stil a while the engine is runing.
Or when I drive slow in warm wether.
The engine gets about 95 degr C
The light goes of in a day or two.

Ehen I tok it to my mercedes dealer ther test computer indicated an error in air/fuel mixture.

Do you think I need to replace the O2 sensors?


Best Regards
Jonny

Josh K

That would make sense. It could also be your mass air sensor, but you'd have to take it to the dealer to pull the codes to be sure.

clarkspark

Is 'check engine' light the same as 'Service due now'? When I turn on my CLK320 99, it shows the 'service due now' light for about 30 secs or less, and then goes away. Is that the same? My car has 43,795 miles on it. Help please

Brian_I.

No, Service Due Now is just a mileage-sensitive warning to remind you to take it in for regular maintenance not that there is actually a problem. We are talking about a separate light in the cluster that says Check Engine. There are instructions in the manual that you can follow to remove the Service Due message.

SoCalCLK

The Check Engine light comes on when the car senses something wrong or malfunctioning (such as a bad MAF sensor, blown spark plugs, etc)

The Service Due Now light means that your car is in need of a regualr service, such as an oil change or coolant flush. This light is triggered by Mercedes' FSS (Flex Service System) that is a program in your car that tells you when to take the car in for service due to your driving habits, the amount of wear and tear you inflict on it, etc. Hope this helps!

Brian_I.

If you're not getting the right air/fuel mixture then most likely it's your O2 sensors but without the codes it's not guaranteed. You can either take it to a mechanic or to the dealership and have them plug into the OBD port and give you the error codes or you can just buy a tester and do your own diagnosis. If you want to drive your car over to Los Angeles I will let you use my tester for free.

clarkspark

Thanks Samoan_Ridah & SoCalCLK! This helps. Unfortunately I didn't get a manual with mine. (Bought it from used car joint, cheap ba$t@rds) Anyways thanks!

Brian_I.

Do a search on the topic. I know there have been posts on exactly how to do this.

mikeyclk

My check engine light went on about a week ago. Then it went off a couple days later. (I filled the tank in the interim so I dont know if that had something to do with it)

Then on again a couple days ago and off again now???????????