C230 Gas Gauge Failed

[DMarble]

Just last night the gas gauge in my C230 dropped to empty and the reserve fuel light comes on intermittantly. We had driven less than 20 miles since filling up. I thought the
gauge and light were two different circuits. Has anyone had this experiance with a C230. I will be contacting the dealer soon as the car is under Warranty.

[rbauman]

I had the same problem at 10k on a 98 C230. The dealer repaired under warranty. I think it was caused, according to the dealer, by fuel and the type of sensing materials used in the fuel sensor. Good Luck!

[DMarble]

I would hope that fuel would not have a detrimental effect upon the fuel gauge sending unit. As for the type of fuel, we have only put in 91 Octane Premium since we purchased the car at 5K miles. What kind of mileage do you get on the hwy with yours. We got 32.5 on a long (2K) trip to Texas that was way better than I expected. The car runs great and is more fun than my 88 E.

Same thing happened to me on my wife's 1995 C280. Turned out to be "contaminated fuel." Try using up the tank as much as possible and refilling with another brand. It may take a couple of tankfulls to completely come back to normal, but if your case is as mine, it will correct itself.

My situation was somewhat interesting, since we own both a 1995 C280 and a 2000 ML320. Due to a promotion by BP gas stations in our area, the cost for BP gasoline was cheaper than the Exxon that we normally always use. Both my wife and I filled our Mercedes with BP gasoline, but from different gas stations. As soon as we filled the tanks, the gas gauges in both vehicles started acting irregularly with hers showing empty (with the low fuel light going on and off) and my ML320 only showing 3/4 of a tank when I know it was completely filled. I am not sure what they put in BP gasoline (could be an additive that modifies the fuel dielectric and thereby effects the resistive reading of the fuel sending unit), but since switching back to Exxon the gas gauges in both cars have been working perfectly for the last 4 weeks. It took about two tanks of gas in the C280 to clear the fuel sending unit and about 3 tanks in the ML320.

Needless to say, we will be bypassing the BP and AMOCO (BP owns AMOCO) gas stations in the future.

A recent "post" on the Edmund's Town Hall ML discussion also had a similar incident since it is known that earlier 98 & 99 ML's were equipped with a problem fuel sending unit. In this case, the Mercedes dealership replaced the fuel sending unit in an ML320 that only showed 3/4 full when the vehicle actually had a full tank. Even with the new fuel sending unit the condition was not corrected. The zone Mercedes service advisor recommended draining the fuel tank and replacing with "new" fuel. This finally corrected the problem.

It would be interesting to know what brand of fuel you used and if this corrects your problem. Hope this is an easy free fix for you!

[DMarble]

That is a very interesting theory. We had been using Amoco
for both the E and the C without any problems, however the station near our hous was closed for underground tank replacement so I filled up at a Shamrock station. The gauge failed the next afternoon with the gauge pointing to empty and the light coming on intermittantly. I have an appointment with the dealor to look at this and change the oil as we are within 2K on the ESS and I would like to change the oil earlier anyway. I will try driving the heck out of this weekend and refilling it with our normal fuel.
I had run the E on Shamrock gas for several years without problems but this certainly seems to parallel your experiance. I will keep you posted.

[jgl1]

In the latter part of 1999 M-B phased into production new style instrument clusters and three-finger contact fuel sending units (FSUs). The clusters use a pulsed power source to measure the sending unit's float position. Unfortunately, these new FSUs are adversely affected by poor Stateside fuel quality.

Complaints regarding fuel gauge accuracy in vehicles using these new components are being addressed by replacement of the FSUs (MY '00 W202 employs two) together with the instrument cluster.

This problem is not limited to C-class vehicles; also affected are CLK (208), E (210), S (220) and CL (215) class vehicles.

[ItalianBenz]

The reason for this is the oxygenated fuels these days corroding the electrical contacts on the fuel level sensors.
If your car is under warr or ext warr Go to the dealer. They have updated fuel level sensors in stock if not. They have to order coded to your chasis. They also modify the new ones before they install them, they removed the float
arm mechanism and put a slight bend to the arm giving the contacts and closer mating surface gotta go.

Guido
Factory tech
14 yrs
500E 85k

[DMarble]

Thanks to all for the replys. I will be taking it in to the Dealer on Monday next week. The service tech indicated that the sending unit and gauge will both be replaced as they are seeing a problem in this area. He also said that they will change the oil even though the FSS is not indicating it is due, still 2300 miles to go. It will be interesting to look at the old parts just to see if there is any visable damage to them. We have always tried to be consistant with where we fill up. I have noticed that most stations here are using 10% Ethanol for the winter gas. However the station I filled up at in New Mexico was using MTBE, Methyl tertiary butyl ether, (no % listed) I wonder if the mix of the 2 might be part of the problem.

[rbauman]

Hey Dave, I'm glad to see all the responses to your question! My 1998 C230 is not compressed and my mileage runs 29MPG city, 32-34 Highway, depending on 75-65mph speeds. I do enjoy to car and recognize it is a compact vehicle with the problems associated with size and wheel base. I haven't had any fuel gauge blips since dealer warranty work. I'm taking a longer trip (3400 miles) this spring and will have best mileage (Highway) numbers then.

[ItalianBenz]

Hey Dave you wont see a defect at all. And you wont get the part its warranty and its goes to mercedes benz for scrap, the technician has to turn the old part in to get paid thats how its works. Its just a float with an external little circuit board that is coated and submerged in gasloline.

[DMarble]

I knew that could not keep the part as it needs to be returned for credit, but I usually request that I be allowed to look at the part(s) for whatever it is worth. Makes me feel better sometimes. Is the new part a new and improved part or is it more of the same.

[ItalianBenz]

Hey dave hmm as far as the part pretty much the same they rework some of the circuitry and the angle on the float arm. Other than that your cool.

[DMarble]

I had the car in for its FSS A Service and the fuel gauge sending units (sensors) were replaced. It appears to be reading correctly now. Hopefully this is a long term fix. I did notice that the 2000 ML320 that we had as a loaner had a similar problem as the fuel gauge indicated 3/4 full when I left the dealer ship and 7/8 after we drove about 50 miles then full when I pulled into the dealers before returning it. Would the tank have overflowed if I drove it further? I did not encounter any problems with the dealer not wanting to do the service even though the FSS indicated 2300 miles yet to go. The oil had been changed at 5400 and now at 9000
with the FSS being reset this time. I will continue to change every 4-5K using Mobil 1 15-50W. I may even switch to Mobil 1 in the E next oil change.
Thanks to everyone that replied to my original post as the information was very helpful.
ItalianBenz...I was running late when we picked the car up so I did not get a chance to look at the old parts, although the tech seemed to indicate the same as what you had said.
He also indicated that he has replaced several of these in the last few months.

[David C Klasse]

DMarble. Did you have to pay for the 4500 service? I am assuming you did.
And thanks for posting a follow up! It's always good to hear that your problem is fixed and you figured out the what was causing it.
Do you know what years the fuel gauge was wacky on these cars? I only have heard of it on 97 and later 202s and ML (ML from you). I have a 95 C-class and do not have many problems with the fuel gauge... one or two little quirks, but nothing big. One time I filled the tank with the key in the 2 position (computer on) and it registered it as having only filled 3/4 a tank! So I now only do it with key in position 0 or 1! No problem since. Also, it never quite registers FULL, it's always just a tad below that line.
Again thanks for posting a follow up!

[DMarble]

I purchased the car with 5400 miles on it from a Non MB used car lot that in fact was the original owner. They had 16 of these that were used for incentives for their sales people.
so I got to take my pick of the litter. I checked the title
in carfax and called the originating dealer to verify their story. They had just changed the oil but did not reset the FSS. I had run it another 3600 miles with the FSS showing 2300 to go when I had the gauge problem. Since the trip to the dealer is 130mi round trip, for me there was no question about getting the A service done at the same time fortunatly the dealer agreed.
They were very good about it and there was no charge for anything. The car was done early & washed and it appears to be a job well done. I hope that all future services go this well.
I do not have any information on other models that may have this problem and my observation of the gauge behavior in the ML is just that an observation, it may not be subject to the same problem but that one sure acted funny.
As far as indicating the proper level, the original gauge was so close I could look at it and tell how much fuel I would be able to put in +/- a half gallon. It was dead on until the failure. The new gauge seems to be accurate but it will take a few fillups to prove that out. I do have a problem getting fuel into the tank as the auto shutoff nozzle will shut off constantly and I have to baby it to get the tank full. I have tried several different pumps with only slight improvement. I cannot get the nozzle more than half way into the filler tube because the large plastic shield that is installed on the nozzle for vapor recovery interferes with the gas cap door on the car. Do you encounter this problem? The stations in Texas used a spring loaded bellows with a vacuum on it for vapor recovery and that worked fine.