P0788 4-5 Shift Malfunction

How to Fix P0788 4-5 Shift Malfunction


If you’re experiencing a P0788 error code on your vehicle, it means that there is a malfunction in the 4-5 shift. This can cause your vehicle to shift poorly or not at all, which can be frustrating and dangerous. However, with a little bit of knowledge and some DIY skills, you can fix this issue yourself. In this article, we’ll provide you with step-by-step instructions on how to fix P0788 4-5 Shift Malfunction.

Step 1: Check the Transmission Fluid

The first thing you should do when you encounter a P0788 error code is to check the transmission fluid. Low or dirty transmission fluid can cause a variety of transmission problems, including the 4-5 shift malfunction. To check the transmission fluid, follow these steps:

  1. Locate the transmission dipstick under the hood of your vehicle.
  2. Remove the dipstick and wipe it clean with a rag.
  3. Reinsert the dipstick and remove it again to check the fluid level.
  4. If the fluid level is low, add more transmission fluid until it reaches the appropriate level.
  5. If the fluid is dirty or discolored, it’s time for a transmission fluid change.

Step 2: Inspect the Transmission Solenoid

If the transmission fluid is not the issue, the next step is to inspect the transmission solenoid. The solenoid is responsible for controlling the flow of transmission fluid in the transmission. A malfunctioning solenoid can cause the 4-5 shift malfunction. To inspect the solenoid, follow these steps:

  1. Locate the transmission solenoid under the hood of your vehicle.
  2. Disconnect the electrical connector from the solenoid.
  3. Remove the solenoid from the transmission.
  4. Inspect the solenoid for any signs of damage or wear.
  5. If the solenoid is damaged or worn, replace it with a new one.

Step 3: Check the Wiring and Connectors

If the solenoid is not the issue, the next step is to check the wiring and connectors. Loose or damaged wiring and connectors can cause the transmission to malfunction. To check the wiring and connectors, follow these steps:

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  1. Inspect the wiring and connectors for any signs of damage or wear.
  2. If the wiring or connectors are damaged or worn, replace them with new ones.
  3. Ensure that all connections are tight and secure.

Step 4: Replace the Transmission

If none of the above steps fix the issue, it may be time to replace the transmission. This is a more complex and expensive fix, but it may be necessary if the transmission is beyond repair. To replace the transmission, follow these steps:

  1. Remove the old transmission from the vehicle.
  2. Install the new transmission in the vehicle.
  3. Connect all wiring and connectors to the new transmission.
  4. Fill the new transmission with the appropriate amount of transmission fluid.


Fixing a P0788 4-5 Shift Malfunction can be a daunting task, but with the right knowledge and skills, it’s possible to do it yourself. By following the steps outlined in this article, you can diagnose and fix the issue, saving yourself time and money.


1. How do I know if my transmission solenoid is malfunctioning?

You may notice that your vehicle is shifting poorly or not at all. You may also see a P0788 error code on your vehicle’s diagnostic system. If you suspect that your transmission solenoid is malfunctioning, it’s best to have it inspected by a professional mechanic.

2. Can I drive my vehicle with a P0788 error code?

It’s not recommended to drive your vehicle with a P0788 error code. This can cause further damage to your transmission and potentially lead to a more expensive repair.

3. How much does it cost to replace a transmission?

The cost of replacing a transmission can vary depending on the make and model of your vehicle and the extent of the damage. On average, you can expect to pay anywhere from $1,800 to $3,500 for a transmission replacement.