Low or contaminated transmission fluid, reducing heat transfer and lubrication; Restricted transmission cooler or coolant flow, often due to a clogged cooler or faulty thermostat; Faulty transmission fluid temperature sensor sending incorrect high readings; Heavy towing or hauling without auxiliary cooling, causing sustained high fluid temperatures; Internal transmission wear or slipping clutches generating excessive heat; Malfunctioning transmission control module (TCM) or wiring issue in the sensor circuit

DTC codes / P02xx · Fuel and air metering (injector circuits) / P0218

P0218Transmission Over-Temperature Condition

Q: What does code P0218 mean?

Transmission Over-Temperature Condition. P0218 indicates that the transmission control module (TCM) has detected a transmission fluid temperature that exceeds a calibrated threshold, typically around 150°C (302°F). The computer sets this code when the temperature sensor inside the transmission reports an over-temperature condition for a sustained period, often triggering a fail-safe mode to protect internal components.

P0218 indicates that the transmission control module (TCM) has detected a transmission fluid temperature that exceeds a calibrated threshold, typically around 150°C (302°F). The computer sets this code when the temperature sensor inside the transmission reports an over-temperature condition for a sustained period, often triggering a fail-safe mode to protect internal components.

SystemPowertrain

Code typeGeneric (all makes)

SeverityHigh

Fix difficultyIntermediate

AreaFuel and air metering (injector circuits)

Symptoms you may notice

Transmission warning light or message on the dashboard
Harsh or delayed gear shifts as the TCM enters fail-safe mode
Transmission may slip or refuse to shift into certain gears
Burning smell from overheated transmission fluid
Often no symptoms besides the warning light, especially if the over-temperature event was brief

Common causes, most likely first

Low or contaminated transmission fluid, reducing heat transfer and lubrication
Restricted transmission cooler or coolant flow, often due to a clogged cooler or faulty thermostat
Faulty transmission fluid temperature sensor sending incorrect high readings
Heavy towing or hauling without auxiliary cooling, causing sustained high fluid temperatures
Internal transmission wear or slipping clutches generating excessive heat
Malfunctioning transmission control module (TCM) or wiring issue in the sensor circuit

How to diagnose and fix it

Check transmission fluid level and condition; top off or replace fluid if burnt or low
Inspect the transmission cooler and lines for restrictions or blockages; clean or replace as needed
Test the transmission fluid temperature sensor and its wiring for resistance and continuity
Verify coolant level and engine thermostat operation, as engine overheating can affect transmission temperature
Use a scan tool to monitor live transmission temperature data and confirm sensor accuracy
If the sensor is faulty, replace it and clear the code; if the TCM is suspect, perform circuit tests before replacement
Address any internal transmission damage by consulting a transmission specialist for further diagnosis

Overheating Clues Beyond the Sensor

A faulty engine coolant thermostat can cause the transmission to overheat because the transmission cooler relies on engine coolant flow to dissipate heat.
The transmission fluid temperature sensor may be part of the valve body harness, and a chafed wire can short and report false high temperatures.
After a fluid and filter change, air pockets in the cooling system can cause temporary over-temperature readings until the system purges.
Some vehicles set P0218 during extended idling in gear, especially in hot climates, without any actual component failure.
A restricted radiator or failing water pump can reduce coolant flow to the transmission cooler, leading to overheating that mimics a transmission fault.

Can I keep driving with P0218?

If the transmission warning light is on, avoid driving long distances or under heavy load, as continued operation can cause permanent internal damage. Stop safely and check fluid level if possible; if the light remains on or symptoms worsen, have the vehicle towed to a repair shop.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.