In case you notice that your BMW suddenly isn’t nearly as powerful as it used to be or that it won’t rev past 3,000 RPMs, you can almost be sure it has activated limp mode. Luckily, that doesn’t mean something serious or expensive has broken, but a thorough diagnosis is necessary.
The limp mode BMW, just like on all other cars, means the ECU (engine control unit) has noticed a serious fault somewhere in the engine or transmission. And as a self-preservation method, the ECU triggers limp mode, which limits the power output, engine speed, and the transmission from going into gears higher than third as an effort to minimize any potential damage.
What Is Limp Mode in a BMW
The limp mode BMW meaning, which is short for limp home mode, is an ECU setting that’s activated only when the ECU self-diagnostic system notices a serious or potentially serious fault somewhere in the drivetrain. For example, if the oil pressure is too low or if the camshaft or ignition timing is off.
Both cases can potentially destroy the engine, especially if you continue driving aggressively. To prevent that but still allow you to get to a repair shop, the ECU doesn’t shut down the engine but changes the engine programming in order to minimize the chances of damage.
For example, if the camshaft timing is off because of a loose timing chain, lowering the engine power output and speed reduces timing chain stress and the chances of it breaking or jumping on the sprockets. If that were to happen, the valves would hit the pistons, and the whole engine would be ready for the scrap yard.
That’s why it’s extremely important to do a thorough diagnostic of the entire engine and transmission whenever the vehicle enters limp mode. Also, absolutely avoid turning off limp mode manually or deleting fault codes because, again, the limp mode BMW is rarely triggered by a minor issue.
BMW Limp Mode Symptoms
The symptoms of BMW limp mode are almost impossible to miss or confuse for something else. First off, the power will be severely limited to the point where it takes you more than ten seconds to reach 30 mph, even at full throttle. Furthermore, the transmission shifting early and not going past third gear is also impossible to overlook.
Naturally, you will see a check engine light as well, and possibly other warning lights depending on the problem. Also, the top speed will be capped at 30-50 mph, depending on the model. It’s also worth mentioning that limp mode doesn’t have a designated warning light, so these symptoms are the only thing that will reveal it.
Luckily, limp mode usually activates for the first time while driving, and it feels like the gas pedal cable snapped, especially if you are driving enthusiastically. Lastly, here is a full list of limp mode symptoms, including some that may be difficult to notice or might lead you to believe some other systems have suddenly failed as well.
BMW Limp Mode Symptoms – List
- No turbo boost
- The engine won’t go over 3,000 RPM
- Transmission won’t shift past the third gear
- Engine power is significantly lower
- Check engine light, possibly in combination with other warning lights
- The top speed is limited to 35 mph (the speed varies between different models)
- Some auxiliaries like the AC may stop working
What Causes Limp Mode BMW
Unfortunately, there are so many things that can trigger limp mode, making it virtually impossible to list all of them. The BMW limp mode causes range from a blown head gasket, transmission damage, stretched timing chain, and faulty sensors to low fluid levels, a faulty ECU, or even a worn-out engine mount.
Come to think of it, it’s easier to list the things that can’t cause limp mode, and those would pretty much be the windows, body parts, paint, and maybe the radio antenna. Maybe I’m exaggerating a bit, but it’s not far from the truth, either. Still, it’s good to know that the limp mode is a pre-programmed ECU setting meaning that the symptoms are the same regardless of the exact cause. In the end, we will try to list some causes, but they might be too broad.
BMW Limp Mode Causes
- Engine moving components damage
- Blown head gasket
- Timing chain system damage
- Faulty sensors
- Damaged wiring
- Faulty ECU or other control modules
- Ignition system problems
- Fuel system problems
- An old battery
- Worn-out engine mounts
- Cooling system problems
- Lubrication system problems
- Low fluid levels
- Low oil pressure
How To Fix Limp Mode BMW
So, how to fix limp mode BMW? Before even attempting to fix limp mode, you first need to find out what’s causing the problem. So, the first course of action, unless there are other symptoms present, is to scan the fault codes. With that, a generic OBD2 scanner can help if you are lucky, but it’s not something we would recommend for limp mode.
BMW has its own fault codes called DTCs, not to be confused with its dynamic traction control system with the same abbreviation. Those fault codes are significantly more thorough and precise, but you can only scan them with BMW-specific scan tools or more expensive professional scanners that support BMW DTCs.
After that, if the cause isn’t too obvious, consult a BMW specialist. A BMW dealer may help, but relying on a reputable third-party BMW specialist is a better idea. And if the fault codes don’t reveal anything concrete, physically inspecting the systems to which the DTCs pointed is the only thing you can do.
But other than that, there is not much more we can tell you. As we mentioned previously, the causes vary so much that even trying to explain how to fix it and estimating the cost or time it takes to fix it is impossible since it can be anywhere from $50 to thousands.
Q: What triggers limp mode?
Virtually any drivetrain, electrical, or safety system fault can trigger limp mode. That ranges from low fluid levels to a faulty ABS system, bad engine mounts to a blown head gasket, worn-out piston rings, damaged wiring, transmission problems, etc.
Q: Will driving in limp mode damage the car?
Driving in limp mode won’t necessarily damage the car; that depends on what triggers limp mode. That said, the limp mode is, more often than not, an indication of a serious drivetrain problem that will ultimately cause a lot of damage if you continue driving for too long.
Q: Can a bad battery cause BMW to go into limp mode?
Yes, a bad battery can cause a BMW to go into limp mode. An old or damaged battery can interfere with sensor signals as well as ECU voltage, both of which can trigger limp mode.
Q: How long can you drive a BMW in limp mode?
Depending on what’s causing the limp mode, theoretically, you could drive your BMW indefinitely. However, avoid driving it in limp mode as much as you can, at least until you find out what’s causing the problem.
Q: Is limp mode expensive to fix?
The BMW limp mode fix cost doesn’t necessarily have to be high; in some cases, it can cost as little as $50. But since the limp mode is such a broad symptom, it can also cost thousands of dollars to fix.
Q: What speed does a limp mode do?
Depending on the car model, limp mode usually does between 30 and 50 mph. Along with the driving speed limit, there will be a significant reduction in engine power as well as an engine speed limit.
Q: Does limp mode affect the transmission?
Yes, the limp mode does affect the transmission, but only if it’s automatic. An automatic transmission in limp mode will usually refuse to shift higher than third gear.
Q: Is limp mode serious?
Limp mode isn’t necessarily serious, but you should never take it lightly until you find out what’s causing it. For example, it could be low oil pressure which will destroy the engine in a couple of days at most, but it could also just be a worn-out engine mount.
The limp mode in BMWs isn’t any different from the limp mode in other vehicles. And while you should never take it lightly in any car, that’s even more true for BMWs, for which repairs are significantly more expensive. The limp mode can indicate an extremely serious issue like low oil pressure, stretched timing chain, a blown head gasket, or even transmission damage. But on a positive note, it could be just an old battery or low fluid levels.