Apparently the TPS (Throttle Position Sensor) which is built into the gas pedal on this 2014 MB CLA250 only lasts so long before it becomes defective under highway conditions and causes the vehicle to go into LIMP MODE. When full acceleration is necessary, the unit will work for perhaps a few months or less, and then continue to fail worse and more frequently with each attempt at full acceleration. At highway speeds, this is an essential feature in a 4-cylinder vehicle such as this one and without the necessary acceleration capability, can expose the driver to serious risk of collision with other on-coming vehicles traveling at highway speeds. This "Limp Mode" features is extremely dangerous and hazardous to not only the driver of their vehicle, but to other drivers around them since they are left in a devastating position of being unable to accelerate normally and as necessary and as one would expect in any vehicle, let alone a Mercedes Benz. Never before have I driven a car that falls out of full acceleration mode only to subject the driver to serious collision circumstances. Whoever the imbecile is at MB engineering who incorporated this Limp Mode Feature should be fired!!! To make matters worse, this cheaply built TPS, which is the cause of the problem in my vehicle specifically, was only warrantied twice by the dealer and now they will not replace it under warranty which is a two-year period. I've only had the part 5 months before it failed again due to poor manufacturing and I had to pay all over again for a new one despite my warranty validity. There have been many other MB owners who have the same complaint for Limp Mode, which tells me that it's definitely not me, but rather the poorly built or engineered vehicle, as a matter of fact. MB has denied having these complaints to me, which of course, is a lie. That's misleading and deceptive business practices in my State and MB needs to live up to its warranty provisions and respect its customers.

- Lincoln, MA, USA

When accelerating hard to overtake, the engine lurches, and the car fails to accelerate further and slows down. The engine fault light then illuminates which switched off by itself after switching the engine off twice. It seems I am not the only person to have this problem as you can see in the comments to this video describing the problem and claiming the problem is a faulty high pressure fuel pump: Https://youtu.be/-sbr28zbofs this seemingly common issue is clearly dangerous as drivers lose the power when they are most depending on it and it seems to be occurring in cars that are not particularly old.

- Niceville, FL, USA

I was driving my car when all of a sudden the car slowed down and the steering became stiff. The pre safe light came on the screen along with "parking brake" "traction control" although the parking brake was not applied. I had to have my car towed home because it was unsafe to drive.

- Houston, TX, USA

See uploaded document protected auto issues for full story. Hennessy Buick, Mazda, GMC sold me a car 8/18/2017 unknowingly I discovered on 2/5/2019 that it had an illegal can blocker/switch (manipulates computer systems in car and tampers true mileage on car) installed in ignition switch. After obtaining emissions test 12/26/2018, several car failures began to happen while stationary at testing center. While in motion that day, several lights began to stop working. In January 2019, while driving the power steering failed causing me to be unsafe as I could not brake, gas or turn wheel. The block affected all items above, excluding wheels & visibility, but due to limitations I was only able to select 3

- Atlanta, GA, USA

While driving at normal street speed "collision prevention assist inoperative" displayed and car would not accelerate. I was in traffic, but was able to exit and pull over and park, turned car off, & back on. Display reset and car normal. Took to dealership immediately-repair was "non connecting pins". too early to tell if this solves. Upon investigation, this is a common issue with 2014 mb and I want to document this extremely dangerous performance.

- San Juan Capistrano, CA, USA

Purchased my new Cla250 in September 2014. In August of 2015 my car suddenly stopped accelerating while driving 65mph on the NJ garden state parkway!. the pre-safe warning was present on my dashboard. Luckily I was able to pull to the shoulder without causing an accident. This could have caused a major catastrophe killing me and others. I restarted the engine and drove to my destination making sure I stayed in the right lane on the parkway. It failed 2 more times while not on the highway but still a very dangerous situation. Took the car (which had 16,000 miles) to a Mercedes dealership when I returned and they performed a series of tests. They found a product technical support system update which involved updating the software. The failure did not occur again until Nov. 2017. I almost got hit by a bus in philadelphia when my car decided to stop accelerating. Finally, driving to the airport doing 70mph the car again displayed the pre-safe warning and rapidly slowed down almost causing a crash on I-78 in NJ. Took the car to a Mercedes dealership near me and they said since the car is 2,000 miles beyond the 50,000 mile warranty it's not covered. They are replacing a series of parts that will cost me over $4,000 to repair! there is no guarantee this will even fix the problem. Is Mercedes waiting for someone to die before they acknowledge this car has a very serious problem? I have to wonder if there has been any crashes involving this car and nobody survived to detail what was happening! the 2014 cla is not safe and Mercedes doesn't appear to be concerned.

- Jamison, PA, USA

Yesterday I was travelling back home from office in the evening on highway, and suddenly my Cla250 started showing message on console saying "pre safe features limited - see operators manual' and "vehicle inoperative - see operators manual" and lost its throttle, I was unable to accelerate, from 50mph I came down to 20mph within seconds and it was very scary as there were vehicles behind me thinking what I was upto. I immediately switched on flashers and tried my best to pull it back to small space between divider and exit, there was no proper shoulder space so got some scratches on my car. I had purchased this car from dealer as certified preowned vehicle just two months ago, and this was first time I was in such pathetic situation. I called roadside assistant and they were ready to send towing truck, meanwhile I turned off the engine and restarted it and all the messages disappeared and everything looked okay. I made a decision to go back home, as if my car were to be towed late in the evening, I wouldn't get car back the same day, and service center is like 30 miles away and there is nobody to drop me back home. So I decided to take it home and cancel towing truck call. Car moved fine from then on. Today I came to office in car fearing when it would stop again. I called the dealership and what they said was "oh don't worry, that must be some software glitch on pre safe condition, if it happens again bring it to dealership!!". so literally I need to put my life and other drivers life at risk to wait and see if it happens again. I like my car, but definitely I don't want to die in it, neither I want to hurt someone else due to this so called software glitch

- Spartanburg, SC, USA

Purchased a Mercedes cla 250C, and have had it became inoperative while driving on the beltway in Washington D.C. traffic, and more recently on the I-5 in san diego on 1/21/2017 during rain at speeds of 60+ mph in heavy traffic. The vehicle decelerated quickly and lost speed. The console popped up flashing message 'pre-safe functions limited' on the console. The vehicle did not respond to accelerator. After coasting to the right shoulder I was hit, by a passing car, and the motorist kept on going.this had happened about 10 time, and I bought the vehicle new. Mercedes aware, yet they would not do anything because they said if the engine light is not on we cant diagnose it.

- Oceanside, CA, USA

With distronic cruise control on at highway speeds when passing a large truck the distronic cruise control takes over and applies brakes hard almost causing and accident. We have had it in a numerous of time but has not been fixed. The car is not safe this has happen a number of times. We have filed a complaint with Mercedes but has denied to a buy back. Want it on record that the system is faulty and is not safe. I have attached pictures of the warning that shows on the dash.

- Cloverdale, CA, USA

Vehicle became inoperative while driving on a highway. Happened twice today on speeds of 60+ mph in heavy traffic. Vehicle decelerated quickly and lost speed, I was lucky to avoid collisions. The console popped up flashing message 'pre-safe functions limited' on the console. The vehicle did not respond to accelerator. After switching the ignition off and on again, the problem temporary disappeared, but then happened again. The vehicle is duly serviced and is still on warranty, there was no accidents or mechanical faults prior to date. Scary and very dangerous. Could have easily injured myself or someone else who would have hit the vehicle which suddenly becomes inoperative.

- Whitehouse Station, NJ, USA

I have had the same issue as many others. I was driving my car down the highway in the left lane at 65 mph. All of a sudden the speedometer dropped to 0 and I could not accelerate. I had to pull over to the side of the road and turn off the car. This first happened to me twice in December 2013. I took it into the dealership and they did several things to try and fix it. They told me they updated the software. I was scared to continue driving the car, but they assured me it wouldn't happen again. But, the same issue just happened to me again (June 2016). Why hasn't Mercedes done anything to fix this? I don't wan to drive a car that loses speed while I'm on a busy highway, it's not safe.

- Santa Rosa, CA, USA

The contact owns a 2014 Mercedes-Benz Cla250. While driving at various speeds, the inoperable pre-safe warning light illuminated and the vehicle began to stall. The failure was persistent. While the accelerator pedal was depressed, the vehicle failed to accelerate. The vehicle was able to restart. The vehicle was taken to a dealer where it was diagnosed that the pins failed and needed to be replaced. The vehicle was not repaired. The manufacturer was notified. The failure mileage was approximately 24,000. The VIN was not available.

- Wantagh, NY, USA

Multiple episodes of "pre-safe functions limited" occurring. When this message appears the car suddenly loses acceleration and you are not able to go above 30 mph despite pressing on the gas pedal. This has occurred on normal 35-45 mph streets but has happened multiple times on the highway when the car is going 65 mph. Luckily, no motor vehicle accidents have occurred because of this issue. The car is able to accelerate and function normally after turning the engine off and on again. Have gone to Mercedes dealer multiple times to fix issue. The first time it occurred, Mercedes updated system software. Next they replaced vehicle sensors. Most recently they claimed the issue was due to oil pump failure. They replaced an oil control valve and oil pan. Four days after the repair I received the same "pre-safe functions limited message, my car stalled while I was going 40 mph. I have returned the car to the dealer once again to run diagnostics. This has occurred many times in the two and a half years that I've owned the vehicle. It is currently at 49,200 miles and has been properly serviced. Each time I bring the car in for this error message Mercedes replaces a new part but it does not solve the problem.

- Romeoville, IL, USA

While driving at highway speed the accelerator pedal suddenly failed. The engine would not respond to any input of the gas pedal. I pumped the pedal, floored the pedal all with no response. The engine would not rev past idle and the car lost speed making changing lanes difficult and dangerous. The error messages shown in the photos appeared in the dashboard. This has happened twice (11/30/15 and 12/6/15).

- Charlestown, MA, USA

What is the problem-pre safe malfunction error when does it happen-while driving is it predictable-no is it safe-no why-the car suddenly loses acceleration, when the pre-safe error comes on. Scenario-driving a cla 250 at 60 mph on a motorway on a quiet road in front of a truck.... pre-safe malfunction kicks in the car slows down and loses accln. The truck driver cannot predict this behavior a this is not a normal pattern to slow down suddenly from 60mph on a quiet freeway. Very very dangerous.

- Clifton Park, NY, USA

While driving my cla that I have only had 4 months the car turned off and said it's inoperable! I was almost hit multiple times, when dropped it of at dealer they wouldn't even give me a loan. I bought this car brand new!

- West Chester, PA, USA

Car had no acceleration while driving in traffic on a major parkway. Vehicle inoperable pre safety features disabled flashed on the message center. Engine light also came on. Vehicle taken to be serviced and the accelerator module replaced. My car seemed okay until it happened 4 more times again while driving on a parkway. This occurred approximately 5 weeks after the car was "fixed". same exact problem and message. Is mb waiting for someone to get killed? so many people having the same problem. I don't need to get in an accident. I thought I was buying a safe dependable vehicle with exceptional service. I should have kept my sonata. I'm really afraid to drive this car again once I get it back.

- Freeport, NY, USA

Recently, every time I MA driving in the rain, no matter how light the rain is, the traction control light comes on and a message stating"pre safe, functions limited, inoperative" shows up. The vehicle has looses acceleration. This happened to me on the freeway today. This is potentially dangerous as it could cause a serious accident. This seems to be a recurrent problem based on a simple online search.

- Edmonds, WA, USA

I was driving and all of a sudden the pre safe mode popped up saying "inoperative" and "see owners manual". the check engine light came on as well as some sort of traction control light. I was nearly in a accident because the car wouldn't accelerate. When getting stopped at a red light the car would not accelerate after pushing the pedal. Then it would accelerate real fast. Luckily I was only 20 minutes from my local Mercedes dealer so I called them and told them I was bringing the car directly to them. This is very scary and from seeing other complaints there must be something that needs to be addressed.

- Smyrna, DE, USA

Accelerating from an intersection after the light turned green, the engine began chugging and thumping. The check engine light came on immediately and the eco light started flashing. The engine stalled several times. We drove straight to the dealership with the car. At every intersection with a red light, it seemed as though the car would stall again. We did make it to the dealership. They kept it for three days, and determined that it was a defective manifold pressure sensor. This is the second time the manifold pressure sensor has had to be replaced. In the first episode on October 9th, 2014, the car died completely and the message "inoperable" appeared in the message screen. The car had to be towed in that time. Both instances required replacement of the same sensor and an update to the software.

- Sarasota, FL, USA