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Old 02-26-2020, 11:41 PM   #1
OURMANDAN
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Limp mode FOG

I am new to the forum but amazed that .. for an E46 which has been around a VERY long time, little seems to be actually, definitively known about limp mode. Lots of guessing .. little solid knowledge. Even how it is defined is hazy. Some say it just limits your speed while others show video of the tach bouncing up and down between 600 and1100 RPM.
I too have a problem with my automatic E46 325i. if I punch it and the tach goes up to about 6000RPM (in manual OR automatic) I go into limp mode too.
This sucks. I get the famous (3 light salute) , and the bouncing tach needle. No code is set ever. The tranny seems fine .. but I don't know how to see Transmission codes .

The one solid "it fixed it when I did this" was from a guy who said it was his throttle body.

other mention I've found says "I replaced the MAF, its the wheel sensors, you need to add tranny fluid) (obviously not the case if you know anything about the E46 tranny) , its the DISA , its the Vanos ..the spark plugs, the coils, The O2 sensor the switch on the gas pedal .. Its the ECU. Its clogged catalysts etc. I've even seen talk that its a governer of some kind that activates at 6000. ONe guy even said it was his water pump!! THis kind of guessing is useless. Maybe there is more than one reason the car goes into limp mode.. and maybe only one. The thing is that no one seems ot know for sure.

So let's do a statistical experiment. Answer me back if you have had a limp mode problem and fixed it .. or got it fixed. Please include your model and year. Don't respond if you replaced more than one thing at the same time, or if it "got a lot better". Because this won't (satistically speaking ) help.

I will tabulate the "Yes I got it for sure" answers , and post them back up here in part 2 ... I'll watch for answers for about 2 weeks. Let's get this Fing Limp mode problem figured out !!!! - Kind Regards -

Last edited by OURMANDAN; 02-26-2020 at 11:43 PM. Reason: forgot to ask for model & year
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Old 02-27-2020, 12:33 AM   #2
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neither do I have any idea what a limp mode is. mentioned a lot, but seems to mean struggling to get home. haven't had that problem. either I'm running or I'm stalled. want to learn so I'm watching this.
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Old 02-27-2020, 06:09 AM   #3
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The first step in diagnosing a problem is to scan the engine computer (DME) and the transmission computer (EGS) for codes. The car goes into the limp mode to protect the engine and/or the automatic transmission from damage. Also, Id have the shop perform a smoke test of the intake manifold. The only way to find all of the vacuum leaks is to smoke test with a professional smoke machine. Find a reputable indie shop that specializes in bimmers at www.bimrs.org. The shop needs to have all of the proprietary BMW software.
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Old 02-27-2020, 08:49 AM   #4
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Quote:
Originally Posted by OURMANDAN View Post
I am new to the forum but amazed that .. for an E46 which has been around a VERY long time, little seems to be actually, definitively known about limp mode. Lots of guessing .. little solid knowledge. Even how it is defined is hazy. Some say it just limits your speed while others show video of the tach bouncing up and down between 600 and1100 RPM.
I too have a problem with my automatic E46 325i. if I punch it and the tach goes up to about 6000RPM (in manual OR automatic) I go into limp mode too.
This sucks. I get the famous (3 light salute) , and the bouncing tach needle. No code is set ever. The tranny seems fine .. but I don't know how to see Transmission codes .

The one solid "it fixed it when I did this" was from a guy who said it was his throttle body.

other mention I've found says "I replaced the MAF, its the wheel sensors, you need to add tranny fluid) (obviously not the case if you know anything about the E46 tranny) , its the DISA , its the Vanos ..the spark plugs, the coils, The O2 sensor the switch on the gas pedal .. Its the ECU. Its clogged catalysts etc. I've even seen talk that its a governer of some kind that activates at 6000. ONe guy even said it was his water pump!! THis kind of guessing is useless. Maybe there is more than one reason the car goes into limp mode.. and maybe only one. The thing is that no one seems ot know for sure.

So let's do a statistical experiment. Answer me back if you have had a limp mode problem and fixed it .. or got it fixed. Please include your model and year. Don't respond if you replaced more than one thing at the same time, or if it "got a lot better". Because this won't (satistically speaking ) help.

I will tabulate the "Yes I got it for sure" answers , and post them back up here in part 2 ... I'll watch for answers for about 2 weeks. Let's get this Fing Limp mode problem figured out !!!! - Kind Regards -
Nice of you to take this on. I agree with your thoughts stated above.

I drive a 2003 330ci (145K on clock). My limp mode issue was solved by a friend of mine who has vast knowledge and experience with the e46. I go to him with lots of questions. His name is Eric. Eric found with his BMW software (1.4) that there was no communication with the EGS. Though I cant state to his checklist of things he checked (or in order checked), I can say he found the specific problem. The upstream O2 sensor cable/wire had gotten pinched between the Valve cover and block where it wraps around behind the engine (pinched ever so slightly on a previous VCG replacement) and over time had rubbed through the outer insulation(s) down to bare wire, thus shorting out a fuse and initiating "limp mode" once the bare wires touched. I'm sure there may be a minor detail of the fix I'm leaving out but this is the jest of it.

Sorry if this isn't what you are asking for..
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Old 02-27-2020, 11:24 AM   #5
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You can scan the fault codes from all the control modules using BMW Scanner 1.4 running on your Windows laptop.
The cable is $20 and the software is free - scroll down for the download link.
https://www.xcar360.com/bmw-scanner-...de-reader.html

I would specifically scan the DME, EGS, ABS modules.

See the BMW Scanner 1.4 links in our Important Threads and Links sticky.
https://forum.e46fanatics.com/showthread.php?t=1130405
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Old 02-27-2020, 12:20 PM   #6
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'03 325i steptronic, ~130k.

Got the transmission fault red gear indicator and went into limp mode only allowing 4th gear (I believe, it was one of the taller ones).

Replaced the battery to solve the problem. Apparently one of the first modules on these cars to be affected by low voltage from a failing battery is the EGS.
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Old 03-03-2020, 08:16 AM   #7
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"Limp Mode" is an oft used term that's often applied all too quickly.

It's genesis was back in the day when I was a young tech at the dealers. The M70 V12 was new than and used in two cars at the time. The E32 750 & the E31 850.

Those cars were the first (in the USA) to use two separate DME's (left & right bank) and EML (electric throttle actuation) with DK motors (electric throttle bodies).

If/when the engine had a higher order of failure with one bank (multiple misfires, high/low fuel delivery) on one bank, it would shut half of the engine down. The car could be driven albeit on very much reduced power with half of the engine to a repair shop. (Bring the car to an authorized BMW dealer, was the advice in the manual) In order to resolve the problem.

On or about the same time BMW also ventured into automatic transmissions that were electronically controlled with the advent of the ZF 4HP22 & 24 EH. (really a hybrid of hydro/electronic control)
If/when failures precluded proper operation and/or loss of power, the transmission could be operated by means of all the valves going limp.
This provided powerflow to reverse & 3rd. gear.
Again making the car able to move to the shop for repairs.

Fast fwd. to the E46 (that's this forum) and I am unaware of any "Limp Home" mode for the M54 engine.
The transmission does indeed have limp home mode.

The automatic transmissions nowadays are much more complex insofar as they work in tandem with the engine. More specifically there is a constant dialog between the DME & EGS computers going on constantly.

Just a few of the things that happen are load calculations against road speed and making decisions as to what gear to select for parameters of economy or performance, based upon load, engine speed and throttle request.

I stated previously we had a car in here a couple of months ago that had two lights on:
Check Engine and the dreaded trans malfunction (Gear wheel) displayed.
I drove the car manually (Steptronic manual selection) and all of the gears in the transmission worked just fine. (It just wouldn't shift automatically)
Once convinced that the trans was fine, we proceeded with the engine light.

Long story short; The MAF was shorted and the EGS had no good values to work with for load calculations.
New MAF, clear codes & test drive returned the trans out of limp mode and back to normal operation.

Lesson here is that an engine (sensor) issue can falsely set a trans malfunction. Because of the interdependent nature of the two working together.

The current breed of BMW V8 engines do have limp home, again as above with the ability to shut half of the engine down.

YMMV.
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Old 03-03-2020, 06:57 PM   #8
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I've had limp mode on a couple E46s:

2005 325i SULEV-The car went to limp mode where the throttle was non-responsive. It had a top speed of 10 miles per hour. The fix was to just erase the DME codes with INPA. This was likely because of water splashing onto the electronics when I was changing the cooling system.

2003 325i SULEV-The transmission was slipping because of old transmission oil. It was stuck in 5th gear and was really slow to accelerate. The fix was a transmission oil change. Another time, the gear cog came up because the alternator was putting out 18 volts. It was stuck in 4th gear this time and the fix was a new alternator.

2002 325i-An unplugged MAF caused the gear cog, but the transmission was able to shift gears. It shifted gears hard.

2003 330i-A bad transmission input speed sensor put the car in limp mode where it was stuck in 4th gear. Replacing the input speed sensor and changing the transmission oil fixed the problem. However, two weeks later, the output speed sensor also failed and put the car into 4th gear limp mode.

2004 325i SULEV-The transmission computer shorted preventing the gear shifter from unlocking. I was able to force the car into drive. However, the car detected that the shifter was not unlocking and put the car into 4th gear limp mode. This one was tough to diagnose as I replaced the gear shifter solenoid and brake light switch and had no success. I ended up putting in a used transmission computer that I had sitting around and the problem was resolved.

If the E46 detects a bad input or output speed sensor, the car will not be in limp mode when you first start it. It will go into limp mode once you drive it a few feet and the car detects that it is moving but the sensor is not sending a signal.

If the E46 detects 3 codes in the transmission computer such as gear monitoring 55, gear monitoring 54, and gear monitoring 53 (gears 5, 4, and 3 incorrect ratio), then the car will put out code 65, which means that the car is stuck in 5th gear limp mode until all the codes are cleared. Removing the battery cable will not take the car out of limp mode. You will need a tool such as INPA to erase the codes.
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Old 03-03-2020, 07:55 PM   #9
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I picked up a 2004 330ci that would go into eml failure mode when accelerating. It had a air path monitoring fault stored. The car had 4 large vacuum leaks, but replacing the mass airflow meter fixed the issue.
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Old 03-03-2020, 08:48 PM   #10
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Thank you Mark. I did use a smoker and it worked fabulously. I adapted mine from a Halloween skoke maker .. Holy cow that made a lot of smoke. I induced the smoke into the power brake line. Strangely while smoke did emerge from teh many leaks I had, non emerged from the open oil fill hole. i'm still not sure why .. especially given the huge tear in the CVG diaphragm I discovered later.
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Old 03-03-2020, 09:17 PM   #11
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Thank you Mr. McCar. This is a repeat replay as my original disappeared .. you taught me a lot just now. I am an experienced mechanic & electronics engineer but had never touched a "holy Beamer" until we fell in love with the one we have. It needed a lot of work .. so I got a power course. I tought Limp mode was refring to "limping it home" ... until you explained. In our case it first appeared after we had corrected almost everything (vacuum leaks and lots of other stuff) and to drive aggressively in near 6000 rpm, but it happened a couple of times just driving along. just over 6000 it was like a governor clicked on & forced the RPM down to 600-1100 rpm

It would bounce there until we restarted. Than all was fine again. Yes we did get the 3 light compliment. I would have labelled it "governer mode". Our tranny has never done anything but work perfectly for the 2 months we've had it. Recently it has stopped .. and post about that separately tonight to pass what I've learned along

I have a question for you. I notice on my generic OBDII device that Transmission data is available .. but my scanner seems to know nothing about it. What tool can I use to retrieve its contents? Maybe there are some clues in there. Also is the gear light ALWAYS due to a transmission fault?
Thanks!!
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Old 03-03-2020, 09:25 PM   #12
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Thanks Michael. Until your post I didn't even know this nice looking 2004 jalopy even had input and output speed sensors. Do you happen to know where I would find those on my 2004 3.25i? Would the illumination of the gear light mean its absolutely a transmission error (ours comes on when we experience some strange governer effect when we hit about 6000 RPM but a simple restart puts us back on the road)?

What does "incorrect gear ration mean exactly? Is there a tool out there that can read transmission errors and give me the meaning in English (German would be OK I suppose lol). Thank you much for the kind & informative replay. I am definitely developing a theory for why the are so many reporting different causes for "limp mode" (See a previous replay.. according to Mr McCar we should not be calling governance "limp mode" ).
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Old 03-03-2020, 09:26 PM   #13
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INteresting. Your experience supports a theory i'm developing about these "all over the map" stated fixes for "limp" mode .. I think "govenance mode" might be a more appropriate name for it per the post from MRMCCar earlier today

Take Care
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Old 03-03-2020, 09:36 PM   #14
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For anyone wanting to know how these E46 automatic transmissions work, read this.
http://v12.dyndns.org/BMW/BMW%203%20...mission%20.pdf

I have most of the tech docs for both the GM 5L40E and ZF 5HP19 on my Google drive.
PM me your GMAIL address if you want a download link.
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Old 03-03-2020, 10:25 PM   #15
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Michael also its encouraging to know you were able to get the tranny unstuck by replacing the fluid. I'm new to the BMWgame .. I've seen that sticker that says something like "engineered for life of the car ...and I think to myself "if I don't put clean fluid in there and the tranny burns up ... the orginal technically DID last for the life of the car" (laughing). But the fact that the cork DOES wear and the particles DO suspend in the fluid (and this was a big problem for GM cars) makes the choice difficult. This copy of the 3.25 seems to have a very solid transmission at 150K miles. I sure want to replace that fluid .. but don't want to make a problem for myself , so let me ask you this.. How many miles on the one you changed the fluid on. Was teh fluid still pinkish red when you removed it or did it look tired and worn? Any particles inthere? 50skid thinks if there have been no tranny problems you absolutely SHOULD replace the fluid. What do you think? Thanks again.

Last edited by OURMANDAN; 03-03-2020 at 10:27 PM. Reason: too many typos
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Old 03-03-2020, 10:38 PM   #16
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Mr. Mcar I reread your last paragraphs and am convinced that the MAF is a "critical component" of the BMW. The original was Siemens in mine when we bought it, so I thought i had the "good one", and with my electronics hat on I would say there isn't much to fail there (maybe the hot wire but its easily checked) but as I came up the curve I realized the BMW (6 2004 and up at lease) has a little circuit board & therefore can fail. Cleaning it to make it all better is BS in my mind unless you plowed a corn field with it or something.

footnote: [For those who care, I'm a cheapskate and was not going to pay 250.00 for a Siemens copy if I could help it. Here is the link for the model I purchased in JAN 2020 based upon high feedback remarks. It works perfectly and the price is great!! This one is for 2004 up (6 pin model)

https://www.ebay.com/itm/MAF-Mass-Ai...2.m2749.l2649]
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Old 03-03-2020, 10:45 PM   #17
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Thanks for the reply HarleyRob,

Your friend's discovery is an important result segways into a pattern I'm noticing. I will soon post a little write up. But let me ask you ; How are you defining limp mode? I thought it meant "limping the car home" , but MrMCar says that's not what it means. If that's the case then I'll call it "governed mode". When you say limp mode, Did your mean the car suddenly went to between 600 and 1100 RPM and bounced quickly between these 2 limits until you restarted the car?
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Old 03-03-2020, 10:59 PM   #18
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I have changed the transmission oils in 5 E46s all with ZF transmissions and have had zero issues:

2003 325i SULEV: 156,000 miles
2003 330i: 117,000 miles
2004 325i SULEV: 214,000 miles
2003 325i SULEV: 166,000 miles
2002 325ci: 165,000 miles

The old fluid has always been dark black and the new fluid was bright red. I've also had one SULEV fuel pump failure and put in a used fuel tank.

The input speed sensor is located behind the valve body and requires removal of the valve body. The output speed sensor is located in front of the valve body and can easily be replaced with the valve body still installed.

That gear cog light does not always mean that you have transmission issues. It could also be caused by a bad alternator, bad battery, or bad mass air flow sensor.

Incorrect gear ratio means that your transmission is slipping too much. That could be caused by worn out clutch packs, bad transmission fluid, or a gear sleeve that has slipped and cannot build fluid pressure. INPA will tell you what codes your transmission computer has. I currently use an Autel MX808, which I bought for $400 on FCP Euro. It may be expensive, but it can scan almost all of the computers on almost every car including Lamborghini, Bentley, etc. I am also able to program car keys with the MX808 for my Hondas, Toyotas, Nissans, and some European brands. The tool can also calibrate steering angle sensors and has many other functions.
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Old 03-03-2020, 11:15 PM   #19
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Hi LLIam ,
So far a lot of good information from some knowledgeable folks. Indeed I've determined there are 2 different definitions for "limp mode" .
#1 MrMcar explained the original original of the word as a condition set which turns off half the engine by making the Transmission valves for "limp"
#2 a "governed" condition where teh car is limited in speed

Here's a 20 second Video that shows you exactly what I was seeing and calling "limp mode" in my own car. Its fixed now, and I know why... I'll beposting a completed write up soon. (By the way I am a lot better looking than the guy who originally posted this).


Last edited by OURMANDAN; 03-03-2020 at 11:16 PM. Reason: added a man joke
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Old 03-04-2020, 07:33 AM   #20
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Originally Posted by OURMANDAN View Post
Michael also its encouraging to know you were able to get the tranny unstuck by replacing the fluid. I'm new to the BMWgame .. I've seen that sticker that says something like "engineered for life of the car ...and I think to myself "if I don't put clean fluid in there and the tranny burns up ... the orginal technically DID last for the life of the car" (laughing). But the fact that the cork DOES wear and the particles DO suspend in the fluid (and this was a big problem for GM cars) makes the choice difficult. This copy of the 3.25 seems to have a very solid transmission at 150K miles. I sure want to replace that fluid .. but don't want to make a problem for myself , so let me ask you this.. How many miles on the one you changed the fluid on. Was teh fluid still pinkish red when you removed it or did it look tired and worn? Any particles inthere? 50skid thinks if there have been no tranny problems you absolutely SHOULD replace the fluid. What do you think? Thanks again.
Ah yes, the "lifetime" fluid recommendation.
Keep in mind that this is BMW's sticker. ZF has handed out countless bulletins (during our annual training taught by ZF instructors) stating that they recommend changing the fluid/filter @ 100,000 Km. That's 62K miles for the ROW.

Personally on my cars, the fluid/filter gets changed every 50K miles. But then it's easy for me...
BTW the HARDEST working fluid an any car is the transmission fluid.
Anymore should be discussed in a new post dealing with transmissions.

Archive searching and continuity is paramount to keeping any forum viable.
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