I have had a few legitamate warnings for bulbs that failed but I have had a couple ghost warnings as well.

From the owners manual:
"Exterior Lamp Failure Indicator
When the symbol and message appear after starting the engine, or if it comes on while driving, this symbol indicates a failure in the parking lamp, taillamps, stop lamp, or low beam headlamp.
If an exterior lamp fails, the indicator symbol will come on only when that lamp is switched on.
If a brake lamp fails, the lamp failure indicator will come on when applying the brake and stays on until the engine is turned off."

What happens when you don't acknowledge the alarm with the R button, does it go away on its own? It appears from the description that the brake light alarm is latching and the other light alarms are self resetting.

However if you acknowledge it then the "two squares" icon appears and the warning persists until the car is shut down, at which time it reappears.

I am wondering if this would help to narrow down the problem.

I had one like that on my W124, that was intermittent, it was a pain trying to catch it in the act. At least on the 124 you just get one idiot light and no annoying beeper.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

I know that the w124 had some sort of large plug-in module near or in the fuse box under the hood that was in charge of all the light circuits that ran to the light failure bulb. It has a bunch of resistors or something in it and if one of them fails or senses less than the required voltage, it trips the light in the dash and also extinguishes that particular bulb. I went through maybe 4 or 5 of those things because each one was showing different lights to be out. First one was a rear side marker light, another was a fog light I believe, another was the front corner light. I jus kept putting used modules in at the junk yard til I found one that wouldn't trip any of the circuits. Yes, it's annoying.

I owned a '99 from new until 2011. For most of that time, bulb failure was indicated. One problem turned out to be the wiring harness for the left fog lamp, which rotted away. But then it came on again and I couldn't find a problem. I'm usually good with electrical stuff, but never solved this one.

I always use the R button, I will try it without the R button.

I am also good at electrical but getting frustrated.

I have a bit of an intuitive feeling it might be my right marker light, it was difficult to seat the bulb but it did seat and light. I may remove the wheel liner and try jiggling the wires to see what happens.

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1999 Mercedes E300TD daily driver sold at 238K miles 106K miles were mine, rust worm got it :-(
2006 Mercedes CDI new daily driver! 56,000 miles May 2016 now 85,625 Apr 2018 and Apr 2019 101,000 miles Apr 2020 109,875. March 2024 135,250, Dec 2024 145,000 miles

No help, but those 99 E300s will make you crazy what with the lamp indicator light. I was rather fortunate with mine.

I will say this, my RT rear lamp assy. went bad, and that was about a $300.00 bill at the MB dealer R&Ring it. How did the meltdown occur? By using a bulb I bought at a retail auto parts seller. I learned to buy ALL replacement bulbs from the MB dealer from then on.

Very important: ONLY buy bulbs from your MB dealer, NOT NAPA or PepBoys or AutoZone, or O'Reilly - I learned the hard way not to buy other than genuine MB dealer supplied bulbs!

My Brother that now owns the '99 E300 still has the ASR / BAS lamp illumination that may have something to do with the vibrating, loose front rt wheel bearing - according to an ex-MB dealer tech. he visits with at his tire shop.

EDSBO - not trying to be critical, but you might want to upgrade out of the W210 MB diesel to a W211 05/06 I6 CDI sedan? The W211 fits my size body in more comfort in the driver's seat, than the W210 - FWIW.

I decided to avoid the V6 configured E320 W211s manufactured from 07 to 09, because of the V6 and it's $2K to fix oil-cooler leaking issue that they develop. Besides - they're basically the same car in the 05 and 06 CDI. - 0.02.....

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'06 E320 CDI
'17 Corvette Stingray Vert

I respect your opinions and have considered moving up to an even newer model but like you found a few deal killers. The oil cooler in the middle of the "V" requiring everything up there including I believe the turbo to be removed. I have heard that it is uncertain whether the fix will be temporary or whether it will have to be done regularly.

Have alos read about a "black death" where combustion gasses blow by the injector threads, erode the head and you then require a new head at even greater expense.

I have also heard rumours about balancing shafts regularly going out destroying the engine. I have not perused this as the previous two defects run $4,000 to $6,000 or more and thus are deal killers.

2005 or 2006 are very tempting. 2007 and newer could be trouble on top of trouble

A good tip but I have already taken each fuse out from the light switch which is accessible from the drivers side of the dash with the access pane removed.

I removed them, hit them with a shot of Caig DetoxIT D5 and cleaned them with a paper towel. They all looked good but I am trying to eliminate everything possible.

Can you be a bit more specific please?

Tonight I removed the passenger's side inner wheel well liner and checked the side marker which I am suspect of but could only get the Light Defective once and it just may have been random, couldn't get it to go on again once reset.

I also took the covers off of the back of both head headlights and all connections look good, no burning, discoloration and everything looks secure.

The tabs have always been broken off the H6W bulb holders and I use a bit of foam rubber to hold them in place once the covers are re-latched.

I am close to replacing all bulbs again with matching pairs.

For additional information some times when the Light Defective meaasge first comes on and I hit the R button it immediately, within a second comes back and I can hot it 7 or 8 times in as many seconds and have the warning come back. Yet, when I stop the car and do a walk around all are lit and upon hitting the R it will stay off.

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1999 Mercedes E300TD daily driver sold at 238K miles 106K miles were mine, rust worm got it :-(
2006 Mercedes CDI new daily driver! 56,000 miles May 2016 now 85,625 Apr 2018 and Apr 2019 101,000 miles Apr 2020 109,875. March 2024 135,250, Dec 2024 145,000 miles

EDBSO:
If the 05/06 CDI weren't a better car, I'd of never upgraded to it.

I have NO interest in the V6 configuration '07-'09 E320 Bluetecs because of the V6 configuration. I dodged a bullet avoiding them. Besides - the 05/06 CDIs are way less $. For IMO a better car.

I was on top of the issues my W210 '99 E300 presented. I just wanted something newer, hence the CDI sedan.

With ALL the helpful hints and experience here - I am going to FWD this ALL to my Brother that now owns my '99 E300.

Great thread/ideas, EDBSO. Ya'll keep the information coming on the W210s!

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'06 E320 CDI
'17 Corvette Stingray Vert

Thank You Skid Row Joe

PROGRESS!!!

I thought I would refresh the common ground connections. As soon as I touched the one on the right hand side of the car almost under the air filter it sheared or simple detached from the body due to rust. This likely caused a poor ground connection. Took it apart, polished the grounding spades with 2,000 sand paper and treated them with DetoxIT D5, drilled a hole beside where it rusted off and used a stainless steel screw and put it back together.

I refreshed the common grounds on the driver's side near the shock tower and in the trunk under the light on the driver's side. All were fine but I refreshed them with DetoxIT D5 and 2,000 sand paper.

Now when I start the car the Lamp Defective warning does not come on. I can go through the turn signals, brakes and back up and the Defective Lamp is not set so YES PROGRESS.

BUT within a minute of driving off it will set. No brakes are being used, no turn signals and certainly not shifting into reverse. Nothing is changed by me still the computer (Hal) thinks that there is a Lamp Defective and I get the Lamp Defective warning. Sometimes upon pressing the R it will stay off for a long time others it will reset to Lamp Defective immediately and 7 or 8 times in a row, YET when I get out of the car all lights are working and lit. The repeated hitting of the R is done without braking or using turn signals.

I am thinking there is a vibration that causes a light to go out for a nano second. I have HID headlights and know little about them but upon reflection they are not on when the Lamp Defective is set so they should be out of the equation.

Am I correct in that this narrows the problem down to the License plate (2) lamps, the front amber corner markers, the front H6W and the two on each side running lights? All of which are on and tapping around and on them does not set the Lamp Defective

Progress but still very frustrating! Hope that some of this helps others.

PS way in the back of my mind I recall something about brake switches causing problems?????

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1999 Mercedes E300TD daily driver sold at 238K miles 106K miles were mine, rust worm got it :-(
2006 Mercedes CDI new daily driver! 56,000 miles May 2016 now 85,625 Apr 2018 and Apr 2019 101,000 miles Apr 2020 109,875. March 2024 135,250, Dec 2024 145,000 miles

I want to know about Brake switches being involved with this problem, if you find that info please post it.

OK, I have some feedback on the intermittent, random brake light issue described in this thread. Granted there are other things being sensed by the Defective Lamp sensor circuit and possible other factors involved.

My wife drives the '99 E300D turbo most of the time over the past year since I bought it from another Forum member. Its been extremely reliable and a very lovely car so I find myself wanting one but I use a wagon most of the time to haul stuff around and the sedan won't do that so until I convert a W124 chassis to a OM606 engine I wil have to be happy with what I've got
So, the first several months she drove it, my wife would run in and tell me the lamp warning popped up. Honestly I admire her constant attention to the issue but it was becoming annoying.
I checked fuses and bulbs including using an Ohmmeter and I replaced the tail light bulbs. Despite what some believe, if you get an aftermarket bulb of the right type it will not burn the taillight lens or housing. There has been a long standing recommendation by some to only use MB lamps because the base is made of nickel (or plated brass) not bare brass and maybe there is some truth to that because bare brass can become corroded with moisture and I've seen that happen but as far as this lamp sensor problem I won't take sides on what lamp to use but I'll use whatever is on hand and most lamps I buy are Osram (Sylvania).

OK, on the issue at hand. Each time I went out and switched the ign sw on it was fine. No Pop Up
But then I drove the car a few times and noticed the lamp popped up it often after going over a bump in the road and always when braking.
I called a friend who is employed as a mechanic and he said there was a defect in the taillight assy on the circuit board where the lamps fit into a plastic holder, something about a bad design and he suggested I speak with the parts counter at the dealer so I did.
I dropped in to see the fellow I know at Autobahn Motors and was informed that he was aware of this being a widespread issue and that MB had changed the tail light assy in the W210 cars but before I could find out the cost for one of these (heck I already knew it would be over a hundred bucks) I received a fone call or something and had to leave.
I was eager to go and have a look at this and I did and saw there is a what looks like tin plating over some metal where the lamp holders are inserted and rotated until in the locked position. There was some erosion on the metal where the lamps contact rubs on the metal substrate and I can see where there could be a problem but it clearly wasn't what I would deem a "bad connection". The fact it happens on a good sized bump in the road may show there is a broken filament in one of the lamps or the lamp holder is momentarily losing good connection, its hard to really diagnose this without some special equipment that would take a half a day to set up.

I ran some crocus cloth (ultra fine grit) over the area where the lamp holder fits, I don't think it removed much metal (plating?) but that reduced the number of pop-ups as they are called around here, but not completely eliminated them. I still get some and only when braking so its definitely associated with a brake lamp. Its the last little gremlin in the car and I too wish it would go away but I'm not into spending $300+ to find out if new tail lights will solve it. Because I just spent more than that for new headlight assys, with Xenon lamps. That I consider more important because I need to see the road at night!

There is possibly a bulletin on this from MB but of course it wasn't made a recall or we would probably have all known about this problem by now.
DDH

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!

Matching pairs isn't the issue, the bulbs must be the proper wattage otherwise the current sensor thinks there is a bad bulb.

Small single filament bulbs come in many wattages and the old standby 1157 now comes in higher wattages too. I've seen many Euro / Japanese cars that post the wattage on the housing to assure the proper ones are used.

If it were my car I would not replace all the bulbs (especially not with rip off Mercedes bulbs), which probably would not fix the problem, which most likely is due to bad connections or bad wiring.

I would:

-remove all bulbs
-remove the fuse that powers the bulbs and put an ammeter in its place
-put the bulbs in one at a time to get an amperage measurement and check it against the bulb's spec current draw. P=E*I where P is watts, E is volts, I is amps
-fix whatever is the cause of the low amperage draw on the bulb(s) and that will probably fix the lamp defective warning.

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked