Mitsubishi automatic transmissions while simple and generally reliable can develop problems, especially at high mileage or if it is CVT transmission. 

If your Mitsubishi has developed erratic shifting or won't shifting at all it can be an indication of a serious problem such as faulty valve body, worn bands, faulty transmission speed sensor, and torque converter but those symptoms can also be caused by low transmission fluid level.

If your Mitsubishi transmission is not shifting normally, first check the transmission fluid level as soon as possible and if needed add the recommended fluid typically Mitsubishi SPIII Fluid or ATC J4 Fluid for vehicles with the CVT transmission. 

In this guide, we go over Mitsubishi transmission problems and steps to help you troubleshoot Mitsubishi transmission problems such as limp mode, no shifting, delayed shifting and slipping. The troubleshooting steps outlined below can be applied to Mitsubishi Eclipse, Lancer, Outlander, Galant, and Endeavor.

Symptoms

Mitsubishi transmission problems quite often are caused by low transmission fluid level. Transmission fluid leaks can develop around the transmission pan gasket.

Common Mitsubishi automatic transmissions problems:

• Mitsubishi transmission will not shift
• Transmission won't go in gear
• Won't shift out of neutral or park
• Mitsubishi transmission won't respond 
• Burning smell from transmission
• Complete loss of drive gear
• Harsh or failed gear changes
• Jumping to neutral while driving
• No reverse gear
• Rattle or judder during accelerations

Some of these symptoms may not be due to a transmission issue. For example, a faulty Mass Air Flow (MAF) sensor, failed catalytic convertor, or accelerator pedal could cause similar symptoms. 

Mitsubishi 4-speed and 5-speed automatic transmission installed on Mitsubishi Lancer, Mirage, Galant and Outlander are overall very reliable with few issues and can easily last over 150,000 miles.

Mitsubishi vehicles equipped with CVT transmissions are known to have transmission problems. Back in 2016 Mitsubishi recalled over 80,000 Outlander and Lancer vehicles with CVT transmissions because of problems with delayed acceleration. 

Causes

Issues that may cause Mitsubishi transmission problems: 

• Low transmission fluid level - Low transmission fluid level can cause a number of issues including erratic shifting, no shifting at all, delayed shiting, strange grinding noises, limp mode, and even check engine light to come on. 
• Worn Bands -  Can cause delayed shifting, shifting at high RPM, harsh shifting, no gear at all, no reverse. An issue on high mileage vehicles with over 200,000 miles. 
• Faulty Vehicle Speed Sensor  - If your Mitsubishi has developed a harsh shift or is stuck in emergency mode (limp mode), the vehicle speed sensor (VSS) may be the problem. The signal from the VSS is sent to the Powertrain Control Module (PCM) and loss of signal due to a bad sensor can cause stuck in gear problems. 
• Brake Light Switch - A faulty brake light switch can prevent shifter to move out or back in Park. 
• PCM / TCU / ECU Software Issue - Software issues can cause erratic shifting or downshifting issues. Mitsubishi transmission may shift to late or gears to drop unexpectedly. Mitsubishi dealer has in the past provided software updates to fix these shifting problems. 
• Wire harness - Damages wire harness from ECU / PCM to the transmission housing can cause shifting problems. For example, your Mitsubishi may not shift at all. 

Problems

Complete loss of drive

Cars that use 4-speed (F4A51) or 5-speed (F5A51) automatic transmission can suffer from a sudden and complete loss of drive and reverse, which makes the car undrivable.

In most cases, this will happen while driving for some time or under heavy load. This issue will remain present even after the car cools down. There will be no check engine light or other symptoms. 

Possible causes 

• Broken transmission pump. There is a coil cushion spring that regulates the engagement of reverse gear, which is very thin. Over time, the spring can break and send metal particles throughout the transmission and damage gears inside the pump. There is an upgraded spring available. 

Harsh or failed gear changes 

Cars that use 4-speed (F4A51) or 5-speed (F5A51) automatic transmission can have an intermittent shift problem that will manifest itself as harsh, delayed, or even failed gear changes.

Depending on the fault, this can happen right from startup or after the car reaches operating temperature. In most cases, there will be a check engine light and corresponding codes stored in DTC memory. 

Possible causes 

• Faulty transmission speed sensor, either input or output. In some cases, the problem might be in the wiring or connector. The resulting errors in reading or communications will upset the gear shift pattern. 

Jumping to neutral while driving

Larger Mitsubishi SUVs that use a 5-speed V5A51 automatic transmission in longitudinal configuration can suffer from intermittent issues with jumping out of gear.

Usually, this will happen while accelerating or going uphill, and it will occur in lower gears. In most cases, the driver will be able to perform manual gear changes. 

Possible causes

• Worn low sprag which is a part of the planetary gear train. If there is excessive wear within this assembly, it will not be able to generate sufficient force to engage gears. However, manual engagement is still possible as it doesn’t depend on this part. Replacing the low sprag or the whole planetary gear train are only available repairs. 
• Clogged solenoids or worn valve body, causing intermittent transmission fluid pressure losses. Depending on the affected solenoids, this may prevent gear engagements. Replacing the valve body with solenoids solves the problem. 

No reverse gear

Mitsubishi Lancers or Eclipse with Jatco JF506E 5-speed automatic transmission can experience a sudden loss of reverse.

In most cases, this will happen right after the transmission fluid has been replaced. Other gears will not be affected by this issue, and there will be no other noticeable symptoms.

Possible causes 

• A band anchor stud removed by mistake when changing the transmission fluid. This is a quite common issue because the fill plug and a band anchor stud are similar and close one to another. This sets reverse band assembly free and prevents the engagement of reverse gear. 
• Fractured reverse drum or worn piston that engages it, which usually happens when driving for a longer time with band anchor stud removed. The free-spinning that happens generates friction and heat, which deteriorates drum and piston assembly. 

Rattle or judder during accelerations

Newer Mitsubishi cars use Continuously Variable Transmissions made by Jacto. Although available in several variants, all of them share several common problems.

An intermittent or constant whining or rattling noise is one of them. This will happen only while accelerating, and may even come in combination with a mild judder. There will be no other symptoms or warning lights. 

Possible causes

• Failed primary or secondary pulley bearing. This is a well-known and frequent issue that affects most of these transmissions. Tracing down the source involves driving at the speed where the noise is the loudest before shifting into a lower ratio. If the noise changes its tone and pitch, the fault is with primary pulley bearing. If there is no change, the secondary pulley bearing is a probable fault. There are aftermarket upgraded bearings available on the market. 
• Worn or failed solenoid regulator valve, resulting in low transmission fluid pressure. As this affects the operation of various solenoids, drivers may also experience slippage and poor acceleration in addition to rattle during accelerations. 

Troubleshooting 

Most of Mitsubishi automatic transmission problems are caused by easy to fix issues such as low transmission fluid or faulty transmission output speed sensor. The steps will help you troubleshoot the majority of Mitsubishi transmission problems. 

How to Check Transmission Fluid Level

If your Mitsubishi transmission is not shifting at all, shifting late or slips the first thing you need to do is check the transmission fluid level.

1. Park vehicle on level ground when possible. 
2. Set the parking brakes and shifter in Park. 
3. Pull the hood release and open the hood. 
4. Locate the transmission dipstick. 
5. Remove the dipstick and clean it with a clean cloth. 
6. Reinsert the dipstick in the transmission. Ensure the transmission is fully inserted then remove it. 
7. Look carefully at the dipstick to determine the current transmission fluid level. The level should be between MIN and MAX marks for the COLD (lower) markings. 
8. If the level is low add transmission fluid level. 
9. Drive vehicle for 15 minutes making sure to manually select all the gears. 
10. Repeat the procedure once the transmission warm-up but this time, the level must be between the MIN and MAX marks for the HOD (higher) markings. 

Checking the transmission fluid level is very easy as long as your Mitsubishi has a transmission dipstick.

Read Transmission Fault Codes

The next step is to read fault codes from the transmission control module or what is known as the TCU. To read these codes you will need a Transmission OBD-II Scanner. Basic code readers will not show a fault code.

1. Park vehicle and turn off the ignition. Set parking brakes. 
2. Locate diagnostic port under the dashboard, driver's side. 
3. Plugin your OBD-II scanner then turn on ignition without starting the engine. 
4. The scanner will turn on. Allow it to communicate with the vehicle. Select Mitsubishi then your particular. 
5. Select Control Units then Transmission. 
6. Select Read Fault Codes from the main menu. 

Fault codes that shows as stored status can be cleared. Any code that has present or current status needs to be addressed before you can clear that code. 

Check Recalls

Check if any open recalls or Technical Service Bulletin (TSB) exist for your Mitsubishi that affects the transmission.

Recalls if they exist are performed free of charge by any Mitsubishi dealer. To check if a recall exists on your vehicle, visit our Check Recalls page. 

Mitsubishi Technical Service Bulletins for the transmission typically update the Engine or Transmsimon control unit software. A Transmission Control Module (TCM) TSBs may program the shift solenoids and therefore improve shift quality. 

The problems in this list do not affect all Mitsubishi transmission. Overall Mitsubishi automatic transmissions are reliable except the 2014-2016 Mitsubishi vehicles equipped with CVT transmissions. 

Checking the basic such as transmission fluid level and read codes from the transmission control module are just the starting point. Reading the fault codes with a transmission scanner can help you narrow the problem even further. Internal Mitsubishi transmissions may need to diagnosed and repaired by a transmission repair shop.