zoink

What an irony.... My W210 E55 check engine light was on yesterday right at the dealer's lot gate on my way out after checking the new R-class.

The car felt fine.... still powerful, no jerkiness, nothing.... So I hope it's not MAF issue. I called a dealer and they are going to charge me $140 to do the diagnosis (which I think only scanning the OBD II).

Now my question:
If I scan OBD II myself and tell the dealer what the OBD II message is, do you think the dealer would still charge me $140 for the diagnosis, or will they skip it? If they skip, I'll save $140.... if not, then it doesn't make any difference.

BTW, I've never scanned OBD II myself.... so do you know where the OBD II connector in W210 E55 is? Also, is $100 OBD II scanner at Kragen / local part store any good?

I haven't used the car for ~1.5-2 weeks. The gas was slightly more than 1/4. Yesterday was my 2nd day in a row I used the car before the CEL went on. I haven't filled the gas up. The gas now is slightly less than 1/4.

I am suspecting the gas is bad (either bad from the very beginning or b/c I haven't used the car for a while) and CEL is related to fuel issues.... fuel filter, fuel pump, etc.

What do you think based on your best judgment?

StapleGun

Fill it up and check the gas cap tightness...that alone can trigger the CEL. Also, yes any OBDII can read the code and clear it and you should have one anyways for your own eidification of problems. The OBDII port should be under the driver's side console. Post the codes you get, maybe we can help once you get them read.

maqsood

You may be able to go to one of your local auto parts store and borrow an OBD code reader. I know quite a few auto parts stores have them and would let you borrow tools (including the scanning tools). Just call and check.

zoink

Thanks.... for $100, I think I'd get one myself especially the E is out of warranty already.... I didn't bother as my E never gave me a problem (no significant warranty work) and my other cars are either still in warranty or a japanese car that never gave me any problem for almost 10 years.

I guess the E is either jealous and thinking that I am going to replace her w/ an R-class, or she was mad that I recently sold her competitive friend

I'll post back some time today or tomorrow.

Fast55

The port is under the dash, drivers' side. Flip up the cover and plug right in. A cheap reader can be had for under $100.00. If you were close enough, I'd read it for you. I think Auto Zone loans them for free. Depending on age/miles, it could be an O2 sensor code, that would be my other guess besides the MAF.

zoink

Thanks for the offer, Fast55. I live up north.... in Bay Area. I'll go to Kragen / Auto Zone this afternoon.... can't wait to know what's wrong w/ it.

I hope it's not MAF (if it is, I think I should notice the power drop, correct?). How much is O2 sensor if it's broken? Any different feeling in power and/or engine?

Grumpy666

Since you haven't driven the car in a while, it might just be slight variation in one of the parameters the ECU trends, like fuel trim, etc. Drive the car normally for a few days - it'll probably go away.

If you get a scanner and pull the code, go here for info: OBD2 Codes

BTW - it's worthwhile to get a scanner that can also reset the light, rather than just read.

zoink

Thanks Grumpy! But I think I'll check the codes first.... just to make sure nothing is serious (hopefully.... no warranty here ).

Zeppelin

Keep in mind also that most things that trip a check engine light are emissions related and are covered under the emissions warranty which is usually 8 years/80K.

zoink

Thanks for the response.... I got the following codes:
- P0170: Fuel Trim Malfunction (Bank 1)
- P0173: Fuel Trim Malfunction (Bank 2)

Anyone knows about this code?

I'm guessing my gas cap or my gas tank pressure. I am going to fill up the gas and see whether it's fixing the problem or not.

Looking at the facts, it seems to make more sense:
- Car hasn't been driven for 1.5-2 weeks
- Gas tank is almost empty (1/4)
- Temperature dropped quite big (quite hot - 60-70F - when driving the car the last time and quite cold - 50-60F recently; and at night is currently around 30-40F)

All of this causing the pressure in the tank changes that I think triggers the CEL.

Any thoughts?

Grumpy666

Fuel trim is a correction factor the ECU uses to maintain the proper fuel mixture. If the amount of change in this parameter exceeds a stored value in the ECU, it throws a code. My guess would be that your weather conditions changed during your down time, which caused fuel trim value to change enough to set the light. As I mentioned in my original post, it will go away as you drive more.

zoink

Many thanks to all of you!!!!!

I filled up the tank.... drove only 2 miles.... CEL was still on..... Parked it in my garage..... turned it off and back on.... the CEL is gone.... yay!!!!!

Everything seems OK now.... and no $$$$ for stealership