Elie

The check engine light came on, on my 2000 E320 4matic. I had just refueled the vehicle 10 minutes prior to the light coming on. I re-tightened the fuel cap but the light is still on. The vehicle is running just fine and I have been driving for 2 days like this. the owners manual says it is a fuel system or emissions issue.
Any ideas before I take it to the dealerships and get raped.?

purplegrog

I'd like to chime in here. I have a check engine light as well, but for an unrelated issue. I changed the plugs to see if that would fix the problem and went to autozone to get the codes pulled. for some reason, when the guy tried to erase the codes, they would not be erased from the system. what gives?

RobertG

If the problem is still there the code will not erase. As far as the other issue with the fuel cap , after few ignition cycles the light will turn off if the problem doesnt repeat it self.You can go to the dealer to get it looked at or you can go to the AutoZone and get it scanned for free and code cleared.

purplegrog

but how can the car make the determination that the problem is still there if the engine is off?

RobertG

It depends on what trouble code you have logged. Some codes will be logged with just the key on, when the system goes through selfcheck

Elie

Thanks for the tip, I will go to autozone and have them look and clear the codes.

fatchance

Go to AutoZone as others have suggested in other threads. You can either have them pull the codes or you can rent an OBDII reader for free.

I rented the code reader and got P0170 and P0173. All the info points to a bad air mass meter.

Tried to clean the meter and put it back in hoping that would solve the CEL, but no luck.

I have found one at here for 184 with free shipping. Anyone find this for less or have dealt with this company before?

http://www.drivewire.com/mercedespar...assmeter.html#

Good luck and let us know what error codes you get.

-travis

Franasia

Elie,

Had the reserve light blinking, which is an indication of gas cap not sealing properly, which then triggered the Check Engine light to come on. I disconnected the negative cable from battery and caused the light to go out. Went well for about a week and then same thing repeated. Replaced gas cap ($17.00) and problem solved, I hope, since it's been over two weeks now.

Hope it helps.

Elie

Went to autozone and got the same codes as "fatchance did": P0170 & P0173. Looked at booklet for code explanation and it said Fuel pressure, MAF, O2 sensors.
Which one is it?

Had autozone reset the system, lite went off.
24 hours later it is back on.

I can try the gas cap since it is cheap.
Thanks all

fatchance

Elie,

I ordered up the MAS (mass air sensor) as all the searching I did on this site as well as benzworld.com pointed to this common failure with the fault codes I posted.

My CEL is off currently and the car is sleeping in the garage while I wait for the meter to arrive on Wednesday. Once the new meter is installed, I'll report back whether or not the CEL is off and stays off.

-travis

fatchance

Just installed the new air meter and wow, I didn't realize the sluggishness until after the new meter was in place.

I did disconnect my battery after installing to clear any lingering throttle settings based on the faulty air meter hoping that adaptation would be faster.

All in all, it drives better than I expected after the replacement.

cheers,

-travis

RobertG

I believe that there is an easier way to reset the settings in the ECM rather than disconnecting the battery, with the key on depress the throttle all the way and hold for 3 seconds?

StapleGun

Next time do a search...not trying to bash you by any means. I did a write up on this now maybe three times on this forum. I purchased my car with a CEL since it was a steal and yanked the same codes...it was like the car was transformed follwing the MAF replacement. For your info, $184 is about as cheap as you're going to get on one of those - I purchased a Bosch through ebay for $200 with shipping.

Just so you know, the codes P0170 and P0173 are fuel trim, left and right banks, respectively. Buy an OBDII scanner....they are cheap now, you can even get it at Sears now.