Will it damage the vehicle? - PeachParts Mercedes-Benz Forum

elau · #1 01-30-2003, 12:27 AM

I know this topic has been brought up. The check engine light came on a few days ago but the vehicle runs fine. Will it hurt the vehicle if I keep driving it? I know it can be a thousand things that cause the light to come on, I am just concern if I am doing more damage before I can get it to the dealer.

BTW, the light came on when my wife put gas in the vehicle. I opened and closed the gas cap and the light went out for a few days. Now it is back and stays on no matter what I do. Please help!!

tabo · #2 01-30-2003, 01:48 AM

does it jerk when you accelerate? maybe you can try to unplug the battery for 20 seconds.. and see if the light comes back on.. do you have a ob2 diagnostic computer handy?

Gilly · #3 01-30-2003, 06:47 AM

If she left the truck running while the gas cap was off, then that's why the light is on.
Disconnecting the battery will do no good.
It's doubtful any harm will result if the truck is running good.
Did the low fuel light flash prior to the check engine light? This is an indicator of an evaporative emission leak, which is what is set if the truck is running with the cap off or loose.
If this is what happened, be sure to tell the service writer that she did, it makes less guess-work for the mechanic.

Gilly

elau · #4 01-30-2003, 09:26 AM

I do not think the low fuel light flushed. Then again I was not there when the light first came on. The car runs perfect except the light stays on. I drove it myself and there is no ant strange behavior whatsoever.

I do not have a ob2 diagnostic computer.

#5 01-30-2003, 03:19 PM

After replacing the gas cap, having the light go off and then back on, and then having it come back on after disconnecting the battery, the gurus finally diagnosed a faulty mass air flow sensor.
I suspect the same for your 98.

elau · #6 01-30-2003, 04:11 PM

Did you replace the faulty sensor? Or you just keep driving it? If you replaced the sensor, how much was it and can I do that myself? Thank for the help.

#7 01-30-2003, 07:05 PM

I replaced the Mass Air Flow Sensor a few weeks ago. A new sensor costs around $240 and took less than five minutes to install. However, I would have the engine codes read first before just randomly replacing parts in the hope that it resets the check engine light. It's an expensive way to diagnose problems.

Gilly · #8 01-30-2003, 09:42 PM

My thoughts exactly, Alex.
To say "My check engine light was caused by a bad mass airflow sensor, so your check engine light must be caused by a bad mass airflow sensor" is a bit like saying "My ML is red, so all ML's are red".

Gilly

elau · #9 01-30-2003, 11:03 PM

Oh no......I don't mean that I will assume that would be my problem. I was just curious how much fixing the sensor may be. I intend to take the car in and let the dealer check it out. I do appreciate everybody's input.

That Pete Guy · #10 01-30-2003, 11:33 PM

Quote:

Originally posted by gillybenztech
My thoughts exactly, Alex.
To say "My check engine light was caused by a bad mass airflow sensor, so your check engine light must be caused by a bad mass airflow sensor" is a bit like saying "My ML is red, so all ML's are red".

Does the ML reset/relearn like some other German cars?

If I have a gas cap incident in my other car and then correct it, the CER light will disappear after three cold (good) starts.

tabo · #11 01-31-2003, 03:34 AM

and ask them for a diagnostic... they will get a code and if its
P0 170 & OR P0 173
than replace your air mass sensor.. it costs $600 CA for the part.. its not cheap unfortunately...

Gilly · #12 02-01-2003, 09:36 AM

This still isn't the professional way to do it. More than likely it is the mass airflow sensor, but it could also be a unmetered intake air leak. It doesn't take long to check for it. It takes a mechanic to repair these cars, not parts replacers.

Gilly

#13 02-01-2003, 10:35 AM

I am at a loss for some of the posts above since they were directed at one of mine. First, my CEL fault was finally diagnosed by reading the codes and adaptation values at the dealer. The dealer replaced the sensor and then checked to make sure the adaptation loop was working.

Second, I used the words 'most likely' in stating the cause of the fault. In fact our beloved moderator has posted earlier that something lake 80-90% of the CEL codes are related to the air mass flow sensor and I was exercising caution in the same spirt.

Sometimes folks just want to know what the problem might be so they are not caught off guard at the dealer. I responded in that spirit which seemed to provoke some of the responses. For that I am sorry.

elau · #14 02-01-2003, 01:13 PM

Mickey, Gilly,

No apology is needed here. And Gilly, thanks for the insight.

This is exactly what I am doing. Get some professional and non-professional opinions to educate myself with enough information so when I go see the dealer, I know what to expect. That is all. I am not a menchanic and certainly cannot do any of this work myself. I don't even know where the senor is located.

Regardless, it is a very informative post and once again......thank you everybody and keep this site the best there is!!!!

tabo · #15 02-01-2003, 02:14 PM

when you are looking at the engine, it is in the middle left side (passenger side) it looks like a big tube with a plug stuck to it in the middle.. I don't have any pics .. but its the tube right after the air filter box.. its really simple to install I did it in 3-5 mins times.. This is a very common problem for the ML, alot of my friends have experienced this problem as well..