What P0218 means
P means powertrain (engine and transmission). The 0 marks a generic code defined by SAE, so the same number means the same thing across makes. The third character, 2, places it in the fuel and air metering, injector circuits subsystem; the last two digits identify the specific fault.
The transmission control system monitors fluid temperature and sets this code when it exceeds its over-temperature threshold. Heat is the main enemy of automatic transmission fluid and clutches.
What “Over Temperature” means here
The module recorded that the temperature monitored by the transmission fluid temperature went above its over-temperature threshold. Treat it as real until proved otherwise, then confirm the sensor is accurate.
What you may notice
Symptoms depend on the vehicle and on how the module responds to the fault. Any of these can accompany P0218:
- Transmission temperature warning
- Harsh or delayed shifts
- Torque converter lock-up behaviour changing as the system protects itself
Where to start diagnosing P0218
- Check fluid level and condition using the manufacturer's procedure; many transmissions must be checked at a specific temperature.
- Check the transmission cooler and lines for blockage or damage.
- Consider recent towing or heavy loads, which raise fluid temperature legitimately.
Clear the code only after recording freeze frame data: it shows the engine speed, load and temperature at the moment the fault set, which is often the best clue to reproducing it.
Live data to watch
These standard OBD2 values relate to P0218. Support varies by vehicle; a value your car does not report will simply be missing.
| Value | What to look for |
|---|---|
| Transmission fluid temperature | Usually a manufacturer-specific PID rather than a generic one. |
| Vehicle speed (PID 0x0D) | Context for when the temperature rises. |
Further reading
Frequently Asked Questions
What does P0218 mean?
P0218 is the generic SAE J2012 code for "Transmission Fluid Over Temperature Condition". In plain terms, it means the engine computer's transmission fluid temperature monitor has reported "Transmission Fluid Over Temperature Condition".
Can I keep driving with P0218?
Let the transmission cool and avoid towing or heavy loads until the cause is found.
What should I check first for P0218?
Check fluid level and condition using the manufacturer's procedure; many transmissions must be checked at a specific temperature.
Definition source: SAE J2012 / ISO 15031-6 generic DTC definitions. This is the generic meaning that applies across makes; a manufacturer can define a code more narrowly or add its own sub-codes, so confirm against the service information for your vehicle before replacing parts. Written by the OBDAssistant engineering team — see our editorial policy.