Are you having trouble backing up your car? It may seem like an expensive solution to fix, but not always!
There are actually many different things that can prevent the transmission from reversing.
Let’s dive in!
The most common reason your car won’t shift backward is due to low transmission fluid. It can also be caused by a faulty distance sensor or shift sensor. If you have a manual car, there may be a problem with the shifting mechanism.
Although they are far from all possible causes, they are the most common. Here is a more detailed list of the most common causes of a car that won’t reverse.
8 reasons why your car won’t reverse
1. Low Transmission Fluid Level (Automatic)
Your car needs transmission fluid to transfer power from the engine to turn the wheels. If your transmission fluid is low, it could be preventing you from building up enough fluid pressure to move your car.
Usually, when you have a low transmission it will also not make your car go forward, which I assume your car does because you have just been investigating why it won’t go back.
However, checking the transmission fluid level is easy and can tell you a lot about the problem. If the fluid looks super black and dirty, it might be time to change it. If you can see any pieces of metal in the fluid, something may be damaged in your transmission.
2. Transmission range sensor (automatic)
Many cars have a transmission range sensor installed outside the gearbox. This sensor detects the gear you have selected on the shift lever and whether it matches the sensor on the shift lever.
If this sensor miscalculates or reads the wrong information, the transmission may not realize that you want to shift into reverse and will do nothing instead.
The easiest way to find out is to check the values of the transmission control module in the engine control unit. You can often check the live data to make sure the TCM recognizes when the shift lever is in R.
On some car models, there is a setting on this sensor that sometimes needs to be adjusted. A diagnostic tool is often needed to adjust this sensor.
This sensor may also be installed inside your transmission, which could make it difficult to replace.
3. Gear shift sensor (automatic)
Additionally, the shift lever sends information to the TCM about the selected gear. If the shifter sensor sends that your car is in neutral, even if your shifter is in R, it will not move the car.
This is also easier to diagnose with a diagnostic tool to see what information the transmission control module is getting from the shifter.
Sometimes the sensor is built into the shifter and in those cases, you need to replace the entire shifter.
However, some car models do not have a shift sensor, they only use the transmission range sensor in the transmission. You should check this before any repair to ensure you are not replacing unnecessary parts.
4. Defective valve body (automatic)
The valve body inside the automatic transmission controls gear shifts and other transmission functions. If the valve body becomes damaged, it can cause many different symptoms in your car.
Sometimes a shift solenoid can prevent your car from rolling backward, usually located in the valve body. You can replace the shift solenoid separately on some car models, but you need to replace the entire valve body on some car models.
A valve body is quite expensive and you should diagnose it carefully before deciding to replace it.
5. Defective shifting mechanism (manual)
We’ve already gone over the most common causes of automatic transmission, so let’s look at the causes of manual transmission.
The most common cause of a manual transmission not shifting into reverse is a faulty shift mechanism or faulty shift cables.
The shifting mechanism is located on the gear lever, which may also include adjustments. If you haven’t adjusted the shifter in a while, you may need to do so.
Check your repair manual to see if it has an adjustable shifter and how you can do it yourself.
6. Defective shift cables (manual)
Often, if you have a front-wheel drive car, you will have steel cables running from the shifter to the transmission. These steel cables often have adjustments to ensure that your changes are easy and without difficulty.
If you have not adjusted this setting for a long time, it may prevent you from engaging certain gears, such as reverse.
Consult your repair manual for information on how to adjust these cables. Sometimes the adjustment is made on the gear lever of the gearbox or on the gear lever of the car.
Some rear-wheel drive or 4-wheel drive cars have the gear lever directly on the gearbox and in this case, your car does not have these cables.
7. Defective clutch (manual)
A faulty clutch is something you don’t want to happen as it is often quite expensive to repair.
When a clutch is faulty, it can make it difficult to shift. Often when the clutch is bad it will affect all gears, but in some cases, it may only affect the reverse gear.
If you have an older car with a cable pulling the clutch, you may need to adjust the cable after your repair manual’s suggestion.
If you are having trouble shifting through all gears and your clutch is applied too late on the clutch pedal, the cause could be a bad clutch.
8. Broken teeth in reverse gear (manual and automatic)
This is the last possible cause and the one you really don’t want to happen.
In order for the car to move in reverse, you must engage a reverse gear. If this reverse gear is damaged, it could prevent your car from reversing.
Reverse gear repair is usually very expensive and it is usually more cost-effective to replace the entire gearbox or transmission with a used one.
However, this is not very common and you should really check all other causes carefully before looking into this problem.