If an automatic transmission car gets stuck in gear, there could be an issue with the transmission fluid or a worn-out part. Diagnosing and replacing the worn-out part cost can save you a lot of money. However, ignoring the signs can lead to expensive repairs, including replacing the full gear.
Automatic transmission cars get stuck in gear because of dirty or low transmission fluid, a defective solenoid, torque converter failure, or limp mode. The solution includes replacing the converter and changing or topping up the transmission fluid and the filter.
This article will discuss some of the main reasons automatic transmission gets stuck in gear. Read on to learn how to address each of these issues.
1. Dirty or Low Transmission Fluid
When transmission fluid is dirty or below minimum level, it may make your car get stuck in gear.
You can identify dirty oil by its color. Clean transmission fluid is pinkish or dark red. When the color turns to dark brown or deep red, it can’t lubricate the parts well enough, causing increased wear and premature failure of the transmission parts.
How to Fix?
Turn your car engine on and let it warm up. Make sure you have the correct fluid for your car model.
Pull out the dipstick and read the oil level and check the color. It should be between the “add” and “full” marks.
Change the oil if it’s dark brown or deep red. If the fluid has the right color but is at the add mark or below, top up to the required level.
If the car shifts gears after topping up the fluid, it is advisable to drive into a service shop, check and repair any leaks, and flush and replace the fluid and filter.
For this purpose, you can buy the BlueDevil Transmission Sealer from Amazon.com. It can restore shrunken, cracked, and dried rubber seals.
This video demonstrates how to top up automatic transmission fluid:
2. Defective Solenoid
Solenoids help automatic transmission vehicles shift gears. They power a starter or switch, and they help the car computer detect speed and determine which gear to engage. Then the computer decides which solenoids should open or close.
The transmission fluid flows through the solenoids, allowing a shift in gears. Sometimes the solenoids fail, preventing causing gears to get stuck. The most common cause of malfunctioning solenoids is a failure to move the transmission fluid on time.
The fluid continuously accumulates debris and small metal pieces, changing to a darkish color and making solenoids stop working as intended.
How to Fix?
If the issue with the solenoids is due to dirty or low transmission fluid, you can solve it by changing it or topping up. If the problem continues after topping up or changing the transmission oil, you’ll need to take the car to your mechanic for professional diagnosis and repair.
This video illustrates how to replace faulty transmission solenoids:
Is It Safe To Drive With Faulty Transmission Solenoids?
Usually, transmissions consist of one solenoid less than the number of gears. For instance, four-speed transmissions have three solenoids. These are used for:
- Shift from gear one to gear two
- Shift from gear two to gear three
- Shift from gear three to gear four
If any of the solenoids fail, it will lose control of the fluid during its shift turn. For example, a transmission having a faulty third to fourth gear shift solenoid will successfully shift to gear two and three, but fail to move to gear four.
It’s safe to drive a car with faulty solenoids. However, if you continue to exert pressure on your transmission, it could eventually get damaged. It’s a good idea to repair the vehicle sooner and avoid further damages.
3. Severed Linkage Cable
If there is no communication between the transmission and the shift handle, the car cannot shift gears. Although this is not a frequent occurrence, wires and cables wear out over time due to friction with the metal frame edges of the car.
If the cable that links to the clutch or transmission is pinched off or severed, your car won’t be able to shift gears.
How to Fix?
If all the other options fail to help and you suspect that the cable is the cause, consult your mechanic for verification and replacement. It can be problematic to identify the problem, and it will require advanced tools. This is one scenario where it’s better to leave the fixing to an expert.
4. Torque Converter Failure
If your torque converter is faulty, your car may get stuck in the first gear. The converter transfers power from the engine to the transmission of the vehicle.
Torque converters are usually full of transmission fluid—the converter couples the gear and the engine. In fact, transmission and torque failure symptoms tend to go hand-in-hand.
How to Fix?
If your torque converter is faulty, there’s not much you can do about it— you’ll need to replace it. After you do that, your car should start working as usual again.
If you want a demonstration, this video explains how to replace an automatic transmission torque converter:
5. Limp Mode
Your car’s computer controls the shifting of gears depending on the signal it gets from the solenoids. When it receives erroneous signals or no signal at all, it activates a safety mode called limp mode. This safety mode gets the car stuck in the third or second gear.
How to Fix?
If you notice that your car has gone to limp mode, look for a place to pull over safely. Switch off the engine and leave it to cool down, then restart the vehicle. In most cases, restarting the engine turns off safety mode and reenables the transmission to shift as usual.
Should it go back to limp mode, you should do an OBD scan as soon as possible. If your engine overheats, allow it to cool down before restarting.
Also make sure to check the fluid level. Low oil level is among the leading causes for a car going to limp mode. After topping up the transmission liquid, clear the fault codes using the transmission module.
If that doesn’t fix the problem, you can read the error codes and resolve them using an OBD scanner.
If the issue persists, you’ll need to take a car for a professional diagnosis.
How Automatic Transmission Systems Work?
Automatic transmission uses a plenary-gear system to transfer power through varying gear ratios. Its main components are:
- Sun/central gear
- Outer ring with gear teeth, also known as a ring gear
- Three or two other gears called planet gears
These allow gears to change in ratio as the car accelerates. The cars’ driveshaft connects to a converter, which serves the same role as a clutch linking the driveshaft to the transmission.
How To Reduce Chances of Your Car Getting Stuck in Gear?
To prevent your car from getting stuck in gear, you can practice a variety of safety measures:
- Regularly check the transmission fluid smell, level, and color
- Avoid overfilling the fluid
- Make sure the transmission isn’t exposed to excessive heat
- Avoid towing in overdrive
- Avoiding overloading your car
- Install auxiliary coolers
- Make sure your vehicle warms up thoroughly during cold mornings
- Use the handbrake when parking in a sloped place
- Avoid rocking between gears—if you must, then do it gently
Your automatic transmission can get stuck in gear because of several reasons. If you take immediate action as soon as you notice the signs of your car getting stuck, you should be able to resolve most cases without spending too much money.
Ignoring or continuing to drive the vehicle after it gets stuck in gear can cause you expensive repairs, including replacing the entire transmission. Routinely inspecting your car and servicing it in time can help minimize the risk of getting stuck.