2011 Bluetec Lost Fuel Gage
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2011 Bluetec Lost Fuel Gage
Greetings!
I have a 2011 BT with 50K miles. The fuel gage suddenly stopped working. I thought it might be related to a recent (couple of days) battery change which I did when the old one gave up the ghost. When I changed the battery I kept a regulated 12 volts to auxilary + and - terminals to prevent losing settings and computers. All went fine with no loss of settings. Driving for a day I noticed the fuel gage sitting on empty and panicked, but then I remembered having filled the tank a few days ago. I topped up to be sure and sure enough the gage just sat there. I tried pulling the fuses to the Instrument Cluster (#5 and #28 7.5a in the front SAM) in the hopes it might need a reset - no luck. I went through both SAMS for anything related to fuel and all fuses are okay.
It entirely possible that the fuel gage coincidentally took a powder when I changed the battery, but I'm not convinced. Am I missing something? I'm dreading the news that it could be a sending unit... I have no idea where it is in this car, let alone getting to it.
For the record, I replaced the OEM battery (a VARTA Group 47 AGM) with an Autozone Group 49 AGM - it's a 90a battery vs. the original 80a. The E350's battery tray will accept a 49 and it dropped in without a hitch.
Everything works except the fuel gage. Ideas most welcome!
Cheers,
TY
I have a 2011 BT with 50K miles. The fuel gage suddenly stopped working. I thought it might be related to a recent (couple of days) battery change which I did when the old one gave up the ghost. When I changed the battery I kept a regulated 12 volts to auxilary + and - terminals to prevent losing settings and computers. All went fine with no loss of settings. Driving for a day I noticed the fuel gage sitting on empty and panicked, but then I remembered having filled the tank a few days ago. I topped up to be sure and sure enough the gage just sat there. I tried pulling the fuses to the Instrument Cluster (#5 and #28 7.5a in the front SAM) in the hopes it might need a reset - no luck. I went through both SAMS for anything related to fuel and all fuses are okay.
It entirely possible that the fuel gage coincidentally took a powder when I changed the battery, but I'm not convinced. Am I missing something? I'm dreading the news that it could be a sending unit... I have no idea where it is in this car, let alone getting to it.
For the record, I replaced the OEM battery (a VARTA Group 47 AGM) with an Autozone Group 49 AGM - it's a 90a battery vs. the original 80a. The E350's battery tray will accept a 49 and it dropped in without a hitch.
Everything works except the fuel gage. Ideas most welcome!
Cheers,
TY
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2011 E550 P2 4M Sedan
While the timing is suspect, it seems hard to imagine that the fuel gauge would be affected by a battery change. For one, you had supply power connected. Also, the fuel gauge is inactive while the car is off. It only kicks in when you start the car or perhaps go into accessory II mode (sorry don't have car with me to check).
What about the distance to empty reading on the center cluster - does that still show you have many miles to go?
Have you looked for threads about malfunctioning fuel gauges?
What about the distance to empty reading on the center cluster - does that still show you have many miles to go?
Have you looked for threads about malfunctioning fuel gauges?
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Thanks for getting back thefisch..
I read a bunch of forums on various models, but nothing specific to this W212 BT - some people have had issues with the fuel gage after a battery swap even when voltage was maintained. That makes me wonder if some very sensitive sensor might have tripped; that could require a reprogramming of the fuel sensing system. I just wish I could be sure. I can tell you I was particularly careful in maintaining a stable voltage during the 5 minutes it took to switch out the battery!
The range in the instrument cluster is blank... it doesn't compute the range til empty - nothing there.
The system shouldn't be so sensitve as to require a trip to the dealer for reprogramming if it turns out that it was caused by a battery replacement. It's weird because everything is fine except the fuel gage - no other issues.
Thx - TY
I read a bunch of forums on various models, but nothing specific to this W212 BT - some people have had issues with the fuel gage after a battery swap even when voltage was maintained. That makes me wonder if some very sensitive sensor might have tripped; that could require a reprogramming of the fuel sensing system. I just wish I could be sure. I can tell you I was particularly careful in maintaining a stable voltage during the 5 minutes it took to switch out the battery!
The range in the instrument cluster is blank... it doesn't compute the range til empty - nothing there.
The system shouldn't be so sensitve as to require a trip to the dealer for reprogramming if it turns out that it was caused by a battery replacement. It's weird because everything is fine except the fuel gage - no other issues.
Thx - TY
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How did those other folks solve the issue?
If you're out of options, before you go to the dealer, why not just try disconnecting the battery so there is no connected power? Perhaps by reconnecting you will correct whatever the fault is.
On a side note, I have disconnected power a few times for various reasons and the only saved info I lose if the 'from start' and 'from reset' functions in the trip meter. I have never lost memory seat/mirror settings, window stop points, etc. I do make sure all glass is fully closed before doing so.
If you're out of options, before you go to the dealer, why not just try disconnecting the battery so there is no connected power? Perhaps by reconnecting you will correct whatever the fault is.
On a side note, I have disconnected power a few times for various reasons and the only saved info I lose if the 'from start' and 'from reset' functions in the trip meter. I have never lost memory seat/mirror settings, window stop points, etc. I do make sure all glass is fully closed before doing so.
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One guy took it to the dealer who quickly reprogrammed the fuel gage and he was all set - pretty much the same as this except it was a W202. From what I gleaned from that the experience some parameters need to be fed into one of the computers to enable the gage and for the computation of range. I just don't understand how a computer lost the memory state if power was available. Before changing the battery my wife got stranded in the car when it wouldn't start - she really dragged the battery down by attempting to start it and the car through a whole bunch of errors. So my theory is one of the computers lost it's memory then, not while changing the battery.
There's another forum listing talking about all the strange things that happen to these cars when power is interrupted:
https://mbworld.org/forums/c-class-w...g-battery.html
Today I'll put an ODBII on it and see what I find. I absolutely dread taking the car to the dealer from past bad experiences, but this might need some reprogramming.
There's another forum listing talking about all the strange things that happen to these cars when power is interrupted:
https://mbworld.org/forums/c-class-w...g-battery.html
Today I'll put an ODBII on it and see what I find. I absolutely dread taking the car to the dealer from past bad experiences, but this might need some reprogramming.
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I never hook up an alternate power supply when changing out a battery on any M-B I have owned. I replaced the battery on my E550 not long ago and I had to reset the clock and that was it. I would try the full battery disconnect and see if that helps everything power back up properly.
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Another thing to try is the ECU (or PCM?) reset. Normally this is done for the car to relearn your driving habits, but someone posted once that helped them with some strange issue like their sunroof not being able to close. Just another easy thing to try that doesn't cost you anything but time.
1. Get in car and close the door.
2. Turn key to position 2 (or press the start button twice) with feet off the pedals, i.e. do NOT start the engine.
3. Floor the gas pedal and keep it down waiting 10 seconds when you will turn the key to position 1 (or press the start button once) still keeping the gas pedal down.
4. After key in position 1 lift you foot from the gas pedal and wait about two minutes. In my car the cluster goes black after about 20 seconds but then pops up again after about two minutes. Anyhow, wait two minutes no matter what happens.
5. Turn key off.
6. Go test drive it.
1. Get in car and close the door.
2. Turn key to position 2 (or press the start button twice) with feet off the pedals, i.e. do NOT start the engine.
3. Floor the gas pedal and keep it down waiting 10 seconds when you will turn the key to position 1 (or press the start button once) still keeping the gas pedal down.
4. After key in position 1 lift you foot from the gas pedal and wait about two minutes. In my car the cluster goes black after about 20 seconds but then pops up again after about two minutes. Anyhow, wait two minutes no matter what happens.
5. Turn key off.
6. Go test drive it.
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I did the ECU reset - it worked, but didn't reset the fuel gage. The shift points are much snappier, as expected.
I connected the ODBII I have and it reported no error codes. It also reports fuel capacity at 100% which I'm hoping indicates the sending unit is properly reflecting a full tank since it was just filled. That plus no error codes probably means it's just a finicky fuel gage that's not resetting properly.
Disconnecting the battery next - I'll let it sit awhile and see if the hard reset works.
I connected the ODBII I have and it reported no error codes. It also reports fuel capacity at 100% which I'm hoping indicates the sending unit is properly reflecting a full tank since it was just filled. That plus no error codes probably means it's just a finicky fuel gage that's not resetting properly.
Disconnecting the battery next - I'll let it sit awhile and see if the hard reset works.
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I've tried everything I can come up with. I pulled the main battery out and let it sit awhile - as KEY08 said, nothing was perturbed at all, the clock even reset itself. Everything works except the fuel gage. The dealer says 'it can't do that'... well, it did.
Another other ideas please let me know because this has me stumped.
Another other ideas please let me know because this has me stumped.
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Sorry about that. If you can locate the fuse or connection for the sensor itself, perhaps disconnecting that and then starting the car and reconnecting could kick off something. You may want to send a private message to konigstiger for the sensor location or for other ideas. You could also call up a few independent mechanics and see if they can offer advice or hook up your car for a low price.
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Good idea. I hate these gnarly problems.
There are 2 fuses for the instrument cluster - pulling those works with misbehaving fuel gages on M-class vehicles, but apparently not on the W212. The fuel system has six fuses, 4 in the front SAM and 2 in th rear SAM - I try pulling those and see if that kicks it loose. The dealer's no help.
Cheers,
TY
There are 2 fuses for the instrument cluster - pulling those works with misbehaving fuel gages on M-class vehicles, but apparently not on the W212. The fuel system has six fuses, 4 in the front SAM and 2 in th rear SAM - I try pulling those and see if that kicks it loose. The dealer's no help.
Cheers,
TY
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Good idea. I hate these gnarly problems.
There are 2 fuses for the instrument cluster - pulling those works with misbehaving fuel gages on M-class vehicles, but apparently not on the W212. The fuel system has six fuses, 4 in the front SAM and 2 in th rear SAM - I try pulling those and see if that kicks it loose. The dealer's no help.
Cheers,
TY
There are 2 fuses for the instrument cluster - pulling those works with misbehaving fuel gages on M-class vehicles, but apparently not on the W212. The fuel system has six fuses, 4 in the front SAM and 2 in th rear SAM - I try pulling those and see if that kicks it loose. The dealer's no help.
Cheers,
TY
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I hope it's not the SAM either - just don't need that headache. The SAM is really a fancy fuse box with some internal fuses that normally can't be replaced (although a few adventurous folks have rebuilt them). I'll get it sorted and report back the conclusion. Thanks for the helping hand!
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One more thought that I forgot to mention... I was quite surprised that when I pulled the main battery exactly nothing was lost (except the clock resetting itself). Then I remembered the auxiliary battery. I understand it's job is to allow operation of the electronic transmission, but I wonder if its presence in the system also maintains the state of the electronics in the car? If so, maybe pulling the battery doesn't actually cause a reset of the electronics... a "hard boot". The only other case I could find similar to mine in this forum required a trip to the dealer to "reprogram" the fuel gage - this is essentially rebooting an IC someplace. That leads me wonder whether I should pull both batteries.
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Sorry for the delay in reporting back - long biz trip.
Well, I hate dead-ends, but I've tried everything in the kit bag. Thanks for the many great suggestions and helping hand. Here's what I did:
In addition to everything I above I tried:
- Pulling fuse 42 in the rear SAM which controls the Fuel Pump - left that out for a long time to see if it would reset - NADA
- Since I was planning to replace the auxiliary battery I pulled it and the main battery and let the car sit for a few hours hoping to drain everything and reset the computers - NADA. My theory was that the auxiliary battery could be maintaining the buss at 12V and preventing the computer 'hard boot' I was looking for. Doesn't work. Here's the weird thing... even with both batteries out not a single system lost its memory, with the exception of the clock which resets automatically when you repower the car.
One thing I did notice was when I replaced both batteries and put the key in position 2 the fuel gage did respond for a second and then dropped back to zero. No idea why.
Anyone reading this... listen to KEY08 - on these cars don't worry about maintaining power during a battery change - waste of time. Just replace the battery and forget about the rest.
Konigstiger was a superb help - he went through great trouble helping me diagnose the problem. The last step is to take the car to the ((*#$*@# dealer and have them reset the computers - that's a set of tools I don't have.
Will finish up this thread when I finally get this gage working - what a PITA!
Well, I hate dead-ends, but I've tried everything in the kit bag. Thanks for the many great suggestions and helping hand. Here's what I did:
In addition to everything I above I tried:
- Pulling fuse 42 in the rear SAM which controls the Fuel Pump - left that out for a long time to see if it would reset - NADA
- Since I was planning to replace the auxiliary battery I pulled it and the main battery and let the car sit for a few hours hoping to drain everything and reset the computers - NADA. My theory was that the auxiliary battery could be maintaining the buss at 12V and preventing the computer 'hard boot' I was looking for. Doesn't work. Here's the weird thing... even with both batteries out not a single system lost its memory, with the exception of the clock which resets automatically when you repower the car.
One thing I did notice was when I replaced both batteries and put the key in position 2 the fuel gage did respond for a second and then dropped back to zero. No idea why.
Anyone reading this... listen to KEY08 - on these cars don't worry about maintaining power during a battery change - waste of time. Just replace the battery and forget about the rest.
Konigstiger was a superb help - he went through great trouble helping me diagnose the problem. The last step is to take the car to the ((*#$*@# dealer and have them reset the computers - that's a set of tools I don't have.
Will finish up this thread when I finally get this gage working - what a PITA!
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Thanks for the update! It's obvious You know your way around these cars and gave it the good old college try. You can tell the dealer everything you did and hopefully they will go easy on you and diagnose it quickly and right the ship. Good luck in the final phase!
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Another update....
I finally found time to get the car to an Indy shop. Their computer immediately found a code for the left (driver side) sending unit - no output. I find it an extraordinary coincidence that the sender failed at exactly the same time as the battery died, but it might just be that - freaky coincidence. Konigstiger was kind enough to send me the work instruction to locate the sending unit - unclear that the sending unit can replaced alone or whether the entire left side unit needs to be replaced - I'll find out shortly.
I've read a lot of threads on this forum about W211 and other classes with fuel pump/sender/leak issues, some with low mileage vehicles. I'm tempted to jump ahead of the problem and replace the right side (fuel pump) assembly as long as the mechanic is working back there. I'll sort that out, but it does seem to be an electrical failure.
Part of me suspects these cars, with more sensors than my Christmas tree has lights, are finnicky in the electrical/computer department. Then again, if true this is a problem with every complex modern vehicle I suppose.
I finally found time to get the car to an Indy shop. Their computer immediately found a code for the left (driver side) sending unit - no output. I find it an extraordinary coincidence that the sender failed at exactly the same time as the battery died, but it might just be that - freaky coincidence. Konigstiger was kind enough to send me the work instruction to locate the sending unit - unclear that the sending unit can replaced alone or whether the entire left side unit needs to be replaced - I'll find out shortly.
I've read a lot of threads on this forum about W211 and other classes with fuel pump/sender/leak issues, some with low mileage vehicles. I'm tempted to jump ahead of the problem and replace the right side (fuel pump) assembly as long as the mechanic is working back there. I'll sort that out, but it does seem to be an electrical failure.
Part of me suspects these cars, with more sensors than my Christmas tree has lights, are finnicky in the electrical/computer department. Then again, if true this is a problem with every complex modern vehicle I suppose.
