P0888 Code: TCM Power Relay Sense Circuit

Your transmission is controlled by the transmission control module (TCM) in your vehicle. Because this device is critical to the operation of your vehicle, it must always be in good working condition.

If your scan tool returns a P0888 code, you should get your TCM and transmission checked. This code is one of many trouble codes associated with a fault in the TCM power relay circuit.

What Does the P0888 Code Mean?

Diagnostic trouble code (DTC) P0888 stands for “TCM Power Relay Sense Circuit.” The code is set once the PCM detects a voltage signal issue in the TCM power relay control circuit. If your scan tool retrieves a P0888 code, there’s a high chance there are other PCM or TCM codes that come along with it.

Once the vehicle’s computer detects a voltage issue within the power relay circuit, it’ll trigger fault codes like the P0888. This transmission control system fault is typically caused by an electrical failure. The check engine light might also be illuminated due to this fault.

Note: The definition of code P0888 can differ according to the vehicle manufacturer. Check the appropriate repair manual or repair database for the exact code definition.

What are the Common Causes of the P0888 Code?

• Blown fuse/bad relay
• Circuit issues, such as a damaged wire or poor connection
• Malfunctioning TCM or PCM (possible programming error)

What are the Common Symptoms of the P0888 Code?

• Illuminated check engine light
• Transmission doesn’t shift properly
• Vehicle stuck in “limp” mode

How to Diagnose the P0888 Code

DTC P0888  is a generic powertrain code that can be retrieved on various makes and models. Although the code is common, it doesn’t mean that there’s one solution that’ll work for all vehicles.

If you’re not familiar with diagnosing transmission issues, it might be best to have a trained professional do the job for you. Otherwise, you can go ahead and do it yourself.

The video below will give you an idea of what the diagnostic process might involve:

How to Fix the P0888 Code

Diagnosing any TCM-related trouble code can be complicated, and the P0888 code is no exception. We strongly recommend taking your vehicle to an auto repair shop if you don’t have the tools and experience to repair this fault.

If you have advanced auto repair know-how and decide to work on your own vehicle, it’s best to brush up on your knowledge before attempting any fixes. Repair manuals like those from Chilton or an online repair database contain vehicle-specific repair information, so you might want to check those out before you begin.