How to fix Mercedes GLA Car Shifts Gear To Neutral When Driving
A Mercedes GLA that drops into neutral while driving is usually a slipping transmission: it cannot hold the gear because the fluid is low or burnt, a shift solenoid is faulty, or the clutch plates, bands or gears are worn. To fix it, check the transmission fluid level and condition first, read the fault codes with an OBD2 scanner, get any leak sealed, and replace the worn part. Change the fluid and filter every 30,000 to 50,000 miles so it does not come back.
Neutral is not designed for driving. If the car drops into neutral on the road, you lose drive to the wheels when you need it, so treat it as a fault to fix straight away.
TL;DR
- Cause: low or burnt transmission fluid, faulty shift solenoids, worn clutch plates or bands, damaged gears or torque converter.
- First check: fluid level, colour and smell; then scan for fault codes.
- Fix: seal leaks, change fluid and filter, replace the failed solenoid, clutch or other part.
- Prevention: fluid and filter change every 30,000 to 50,000 miles.
- The 2022 GLA 250 uses a 2.0 L turbo four with an 8-speed automated transmission, listed as Automatic (AM8).
If this is not your case, read How to reset Mercedes transmission?.
Table Of Content
- What is the function of neutral gear in Mercedes GLA?
- What happens to your Mercedes GLA when it drops to neutral gear?
- What is transmission slipping and why does it occur in Mercedes GLA?
- When you are driving, why does Mercedes GLA transmission go into neutral?
- What can you do to resolve the problem?
- Conclusion
1. What Is The Function Of Neutral Gear In Mercedes GLA?
Neutral cuts drive from the engine to the wheels while the steering still controls the direction. This makes it easier to move the car by an outside force. Unlike drive and reverse it is not for driving, and unlike park it does not hold the car still.
You use it when the car needs to be towed, or when the wheels are spun at an emission checkpoint. Neutral also sits between drive and reverse in an automatic transmission.
2. What Happens To Your Mercedes GLA When It Drops To Neutral Gear?
Neutral, unlike drive and reverse, is not meant for driving. It is also not the same as park, which holds the car still.
In an automatic transmission, neutral disconnects the engine from the wheels. The accelerator no longer sends power to the wheels, but you can still steer.
You put a car in neutral when something other than the engine needs to move it, for example:
- Having your vehicle towed
- Pushing it out of a snowdrift by hand
- Pulling it through an automatic car wash
- Spinning the wheels at an emissions checkpoint
If the brakes fail, shifting into neutral can help the car slow down gradually (unless you are going uphill).
3. What Is Transmission Slipping And Why Does It Occur In Mercedes GLA?
Slipping means the transmission tries to hold or change a gear but falls back a gear or drops into neutral. It is a serious safety issue when it happens for no clear reason, and it can happen in an automatic or a manual.
These are the signs.
For An Automatic Mercedes GLA Transmission
An automatic changes gear by itself. It may be slipping if the check engine light comes on, if it tries to upshift and falls back into a lower gear so the engine revs high, if you hear unusual noises while shifting, or if the gear changes are hard or rough.
For A Manual Mercedes GLA Transmission
A manual gearbox may be slipping if it will not go into gear, jumps out of gear unexpectedly, or grinds when you change gear.
4. When You Are Driving, Why Does Mercedes GLA Transmission Go Into Neutral?
It often happens when you are moving slowly or coming to a stop. The transmission slips out of gear, the engine revs up, and then the gear engages again.
Or you press the accelerator, the engine revs, and the car does not move. This is both frustrating and dangerous.
For reference, fueleconomy.gov lists the 2022 GLA 250 4MATIC with a 2.0 L four-cylinder turbo engine and an 8-speed automated transmission, coded Automatic (AM8). Mercedes-Benz USA rates the current GLA 250 at 221 hp and 258 lb-ft. These are the causes to check:
| Cause | Typical sign | Fix |
|---|---|---|
| Low fluid level | Slipping, delayed engagement, leak under the car | Find and seal the leak, top up with the correct fluid |
| Burnt or old fluid | Dark fluid, burnt smell, grit | Change fluid and filter (every 30,000 to 50,000 miles) |
| Worn bands | Hard shifts, slips in one gear | Replace the bands |
| Damaged gears | Noise, will not shift smoothly | Repair or replace the damaged gears |
| Faulty torque converter | Not enough pressure to change gear | Replace the torque converter |
| Faulty shift solenoid | Delayed shifts, will not engage a gear, fault code | Scan the code, replace the solenoid |
| Worn clutch or clutch plates | Engine revs but car does not pull | Replace the clutch or clutch plates |
The Level Of Fluid Oil In Mercedes GLA Is Low
An automatic transmission uses hydraulic fluid pressure to engage each gear. If the fluid level is low, there is not enough pressure to engage the next gear, and many problems follow.
Low fluid is usually caused by faulty seals, ruptured fluid lines, a leaking pan, or a cracked torque converter.
The Fluid In Mercedes GLA Is Overused
Fluid that is not changed for a long time can burn and stop removing heat. Burnt fluid becomes thin and contaminated, parts wear faster, and the transmission starts behaving badly.
The Depleted Transmission Bands In Mercedes GLA
Bands hold the gears in place. If one is worn or broken, changing gear becomes difficult.
The Gears That Are Damaged
Gears wear out when the fluid is no longer doing its job, from heavy use or a low level. Friction damages the gears, so they can no longer shift smoothly into the next gear.
Faulty Torque Converters
In an automatic transmission with a torque converter, the converter does the job the clutch does in a manual. It uses hydraulic fluid to pass engine power to the transmission. If it is damaged, it cannot supply enough pressure to change gear.
The Shift Solenoid Problems
Solenoids are small electrically operated valves that control fluid flow inside the transmission. Hydraulic pressure is what starts a gear change, so a faulty solenoid can cause delayed shifts or a failure to engage a gear.
If the fluid level is fine, suspect the solenoids next. Read the fault codes with an OBD2 scanner to narrow down which solenoid needs replacing.
Clutch Issues In Mercedes GLA
For A Manual Transmission
In a manual gearbox, the clutch is the source of slipping 90% of the time; most of the rest is leaks. Depending on how you drive, a clutch disc can last anywhere from 20,000 to 200,000 miles.
The clutch grips the engine flywheel with friction material (similar to a brake pad) and separates the engine from the gearbox during a shift. If the friction material or the throw-out bearing (the part that moves the clutch when you press the pedal) is worn, the clutch cannot fully engage and the gears slip.
For An Automatic Transmission
Automatics use clutch plates to engage the different gears. If the friction material on the plates is burnt or worn, the transmission may not go into gear, may shift roughly, or may slip out of gear.
5. What Can You Do To Resolve The Problem?
Check whether the fluid is burnt: rub a drop between your fingers and feel for grit, smell it for a burnt odour, and look at its texture. If the fluid is past its best, replace it.
Have a mechanic look for any leak causing a low fluid level, and get it sealed straight away.
Have broken parts replaced at a workshop. Depending on what is found, that can include:
- Faulty seals
- Ruptured fluid lines
- Leaking pan
- Cracked torque converter
- Faulty shift solenoids
- Worn out gears
- Faulty clutches or clutch plates
- Worn out bands
- Old transmission fluid
Regular inspections catch many transmission problems before they cause damage.
Burnt fluid is a common cause of slipping, so change the fluid and filter every 30,000 to 50,000 miles, and check the fluid level and condition regularly. After a repair, a transmission adaptation reset can help; see How to reset Mercedes transmission?. If the problem started in freezing weather, also read Mercedes GLA cold weather problems.
6. Conclusion
Neutral is not designed for driving. It is for moving the car by an outside force, such as towing. A transmission that drops into neutral on its own can cause more damage the longer it is ignored, so check the fluid, read the codes, and change the fluid every 30,000 to 50,000 miles.