Limp home mode in E300 (W210)
 

Yesterday my E300 (188K mi.) was being "test driven" by a guy looking to buy it. Long story short, the car is now in "limp home mode" and was driven in it for 20+ miles. I've looked but haven't found how to get it out of or reset the limp home mode. The car had to be jumped to get it home. The guy tells me it was stuck in second (LHM) before the jump. I was wondering (hoping) that the jump had something to do with the LHM? How do I get it out so I can see if the tranny is OK or damaged? What causes LHM? There are no check engine lights. Am really hoping this is something simple. Low fluid? bad trans controller (or trans fluid getting into it)? I wasn't in the car when it initiated the LHM, so I don't have many details. How do I test? TIA

M-E, in my experience the transmission behavior is related to the limp mode. When my car has set a code in the past, boost was limited or non-existant and if I pushed it hard to go, the tranny would hold a gear all the way up to about 4700 RPM and just sit there not accelerating. It would however, shift if I let off the throttle significantly.

If there is some kind of code, it'll reset itself after 3 successful start/warm up/cool down progressions. I'm surprised there no CEL. Does it light up when you start the car?

As for reseting any codes, you'll need some kind of scanner to read and reset them.

Sorry to hear you're still having problems with this car...

Yes, no codes and the CEL does light when I start the car. It is very frustrating because after the fitting of the new Engine control unit, it was running beautifuly. And now this. I haven't had a chance to see if any codes are stored. That will have to wait until this afternoon. I'll report what I find. The motor still runs fine and doesn't seem to have limited boost. It is weak up to about 15-20mph then pulls fine, but at about 40-45 the rpms get around 3K and above, so I didn't drive it very fast.

Just a thought, check and make sure the MAP line hasn't blown off...

Muleears.......had the same thing happen to my 98 E300 2 years ago and it turned out to be a bad battery. You said it had to be jumped.......how old is the battery? When the current output drops from the battery weird things start happening on these cars including it going into "limp mode"
Hope that helps

The battery is kind of old and he did kill it trying to start it with air in the system. If I put a good battery or fully charge the one in it will it come out of LMH?

LHM is going to be 1st, 2nd and R only. Is that what has happened?

About the only trans code tht OBDII will pull up is PO700 or 715; everything else (the codes that are meaningfull) will require SDS or other high end scanner to "see". In addition to the trans codes, those scanners should also be able to read the trans adapation values which will tell the tech how the trans has been internally adjusting itself recently. The two bits of info should provide enough info to figure out whats gone wrong.

Resetting by disconnecting the batt will not usually clear trans codes and only a few codes (PO380 comes to mind) clear themselves after the 3 cold, hot, cold run cycles.

I suppose its possible its due to a low voltage problem but suspect the prob lies elsewhere.

If it's spinning 3K RPMs @ 45MPH, what gear is it in? It's been too long since I sold my E300, but that doesn't sound right for 2nd, too high a speed. Is the car stuck in 3rd gear?

I beleive it stays in second gear. I can't tell that it shifts.

TMA- I thought LHM was only second and reverse?

I forgot to mention, moving the shifter does nothing. Only when placed in park or reverse. If it is in any of the other selections three or two for instance it stays the same. I'm not sure but I thought it was about 2800 rpm at 45 mph. Wouldn't that be about right for second?

Has never happened to me, but I understand it to be 1st and 2nd; might be 2nd only if set to "Winter"?

Not set to winter, I did check that. I haven't even started it since this took place. I'll do so when I get home this aft. and pull what codes I can (if any) If I can't looks like back to the guy that found the ECM problem.

F-18 If it is (hopefully) the batt. would just replacing it get it out of LHM? Or has it got to be reset somehow? How did you get yours out of LHM?

At the time it happened to me I thought something catastrophic happened just like you. I was out on the road on a sales trip and managed to move it in limp mode to an independent foreign auto place close by.....otherwise I would have tried to trouble shoot it myself. But after he checked it out he load tested the battery and found it to be on its last legs. He said he had seen it before. Once the battery's capacity and current output drops to a certain level the car's system goes into limp or survival mode and shuts down certain electronic components and sensors to match the limited output of the battery. Once he replaced the battery under the seat with a new one it ran perfect again without resetting anything.
You would need that battery load tested before you can make that conclusion.

I'll get the battery tested as soon as I can. If that's it I would be very happy.

Cal - Remember that you can see batt volt using the CCU.

Before you go crazy, take a look at the MAP line - just a hunch. It's easy, just takes a 2 sec look under the hood.