Transmission fluid temperature

What it means

The gearbox computer watches the temperature of the transmission fluid and adjusts gear changes to suit. P0218 means the fluid really did get too hot. The others mean the sensor signal is faulty.

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

• Harsh or odd gear changes
• Overheat warning for the gearbox
• Torque converter not locking, so higher fuel use

Common causes

Most likely first:

• Low or old transmission fluid
• A failed temperature sensor, often part of the internal wiring loom
• Heavy towing or long climbs (overheating)
• A blocked transmission cooler

What to check first

• If the gearbox has overheated, stop and let it cool with the engine idling in Park
• Check when the transmission fluid was last changed
• Overheated fluid loses its protection and should be replaced

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 control system request (P0700), Transmission range (gear selector) sensor (P0705), 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.