hardly worth mentioning
Crashes / Fires:
0 / 0
Injuries / Deaths:
0 / 0
Average Mileage:
76,584 miles

About These NHTSA Complaints:

This data is from the NHTSA — the US gov't agency tasked with vehicle safety. Complaints are spread across multiple & redundant categories, & are not organized by problem.

So how do you find out what problems are occurring? For this NHTSA complaint data, the only way is to read through the comments below. Any duplicates or errors? It's not us.

2003 BMW M3 transmission problems

transmission problem

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2003 BMW M3 Owner Comments

problem #3

Jun 152011

M3 6-cyl

  • 65,952 miles


1. I live in lancaster, ca and when the summer comes around it gets really hot really quick. My BMW M3 2003 which happens to be an smg keeps having problems with the transmission. It causes my transmission to function improperly by shifting to "neutral" automatically. Today, on my way back from work I almost got into an accident when my transmission change automatically from 3rd gear into neutral almost causing the vehicle behind me to crash onto my vehicle. 2. the smg light keeps turning on. I took it to the mechanic immediately and he told me it was the "hydraulic control unit (hcu) with pressure accumulator" which is causing this problem. I notice this problem happens usually during the hot weather since it also happened to me last year around the same time. My BMW mechanic told me this would cost me on or about $3,000 with parts and labor. I got online as soon as I got home to see if anyone else is having the same issues as I am, found out that there are many other BMW M3 smg E46 (2001-2006) owners that are going through the same problem. It's consequences are that since this is the only vehicle I have, I feel my life and the safety of others are at high risk if my transmission changes from any gear into neutral while operating the vehicle causing a major accident to occur. 3. nothing has been done to correct this malfunction. From what I have read and discover online, BMW North America knows about this issue and wants all BMW M3 smg E46 owners to replace the entire hcu which as stated before cost on or about $3,000 with parts and labor. This will only fix the problem temporarily since the problem will persist as the weather continues being above 85-90 Fahrenheit. I don't believe is fair for all BMW M3 smg E46 owners to pay such amount when clearly won't fix such problem. It would be fair if BMW took charge and recall this issue that is putting every citizen in danger due to their mistake in the hcu for all BMW M3 smg E46 vehicles.

- Lancaster, CA, USA

problem #2

Jun 012011

M3 6-cyl

  • 78,960 miles
As you remember, we all spent about six months this past summer figuring out why our E46 M3 smg's were randomly throwing on the transmission check light and randomly cycling into neutral for around 6-15 seconds, displaying a constant "0" during an up or downshift in hot and/or humid weather. We determined after plenty of research and physically removing the smg's hydraulic control unit(hcu), and comparing hard-to-find blueprints of the unit what the malfunction was. The problem was the hcu's hydraulic fluid temperature sensor, which would go bad due to a thin-layered resistor inside the sensor that would microscopically bend and contract over time in avid heat/humidity situations, and send false data to the car's transmission control unit, giving it the illusion that the hcu was overheating and needed to be shut down. To this day, I am still puzzled as to why BMW would program the control module to do such a thing, knowing it would temporarily mame the car's ability to accelerate and/or maintain speed, and thus endanger it's occupants and the safety of other motorists around it.

- Charlotte, NC, USA

problem #1

May 312011

M3 6-cyl

  • 84,839 miles
1. when the temperature where I live reached around 95'F and above my transmission on my vehicle did not function properly. Would shift to neutral automatically resulting in loss of acceleration. I almost got rear ended by another vehicle. 2. ever since the temperature got hot here in AZ, my transmission light has been on and the car keeps going into neutral while driving for about 6-15 seconds before re-engaging. It has happened everyday for the past 4 days, twice while making a left turn at an intersection, which is very dangerous. Many times while traveling straight. Consequences is that my safety is in danger the next time my car is not in gear and someone collides into my car. Very scared of my safety and my occupants. 3. nothing has been done to correct this failure. BMW na knows of this issue, it is due to a faulty hydraulic pump temp sensor that was manufactured incorrectly resulting in the sensor reading an error in the temp and shutting down the smg transmission because it thinks that the hydraulic fluids are overheating(which is not the case). They want BMW M3 smg owners to replace the entire hydraulic sensor hcu unit. Which costs around $3000 to replace in parts and labor. But the problem was the hcu's hydraulic fluid temperature sensor. It's a fairly cheap part to replace, but BMW is not admitting it. Here is link to a discussion on some BMW forums regarding this issue: bmwcca.org/forum/showthread.php?T=4417.

- Vail, AZ, USA

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