Transmission control system request

What it means

P0700 is a messenger. The transmission computer has found a problem and has asked the engine computer to switch on the warning light. The real fault is stored in the transmission computer as another code, which a basic scanner may not show.

Codes in this group

Bank 1 is the side of the engine that has cylinder 1. Sensor 1 is before the catalytic converter and sensor 2 is after it. More terms explained.

What you may notice

• Check engine light
• Harsh, late or missing gear changes
• Gearbox stuck in one gear (limp mode)

Common causes

Most likely first:

• Any gearbox fault: low fluid, a solenoid, a sensor or wiring
• A fault in the transmission computer or its power supply

What to check first

• Read the codes again with a scanner that can talk to the transmission computer
• Check the transmission fluid level and condition if your car has a dipstick
• Avoid towing or hard driving until the real code is known

Have a mechanic confirm. A fault code tells you which system reported a problem, not which part has failed. The same code can have several causes, and they differ between car models. Use this page to understand the code, then have a qualified mechanic test the car before any part is replaced.

After the repair

Once the cause is fixed, the code can be cleared with a scan tool, or the warning light goes out by itself after several trips without the fault. Clearing a code without fixing the cause only hides it for a while. More about clearing codes.

Related codes

Transmission range (gear selector) sensor (P0705), Transmission fluid temperature (P0218), Transmission input and output speed sensors (P0715), Incorrect gear ratio (P0729), Torque converter clutch (P0740), Shift and pressure control solenoids (P0745), Clutch pedal position sensor (manual gearbox) (P0805). All codes.

Written in November 2026. These are generic OBD-II codes, the same on all makes. Causes and repair steps differ between models.