Transmission Fluid Over Temperature Condition
What does P0218 mean?
The P0218 code means the vehicle's onboard diagnostic system has detected: Transmission Fluid Over Temperature Condition. This is a critical severity code.
Common Symptoms
- Check Engine Light or transmission warning light on
- Transmission slipping or harsh shifting
- Burning smell from transmission fluid
- Transmission may go into limp mode (stuck in one gear)
- Transmission fluid discolored dark brown or burnt
Probable Causes (Ranked by Likelihood)
- Low transmission fluid from a leak Very High
- Clogged or restricted transmission cooler High
- Towing or hauling beyond vehicle capacity High
- Failed transmission cooler lines Moderate
- Faulty transmission temperature sensor Low
Step-by-Step Diagnostic Procedure
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STOP DRIVING IMMEDIATELY. Overheated transmission fluid breaks down rapidly and can cause permanent internal damage.
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Check transmission fluid level and condition. Low fluid level reduces cooling capacity. Burnt-smelling dark brown fluid indicates heat damage has already occurred.
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Inspect the transmission cooler (usually in front of the radiator) and cooler lines for leaks, restrictions, or damage.
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Verify the transmission temperature on a scan tool. Normal operating temperature is 175-200 degrees F. Fluid begins to break down above 240 degrees F.
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If the vehicle was towing, allow it to cool completely. Check that you are not exceeding the towing capacity.
Frequently Asked Questions
Can I drive with code P0218?
No. Stop driving immediately and let the transmission cool. Transmission fluid breaks down above 240 degrees F, and continued driving causes permanent internal damage. Burned fluid means clutch packs and seals are already damaged.
What causes transmission overheating?
The most common causes are low fluid level, towing or hauling heavy loads, a restricted transmission cooler, or extended driving in stop-and-go traffic. Hot weather combined with any of these factors accelerates the problem.
Can overheated transmission fluid be saved?
If the fluid has only been mildly overheated (slightly discolored), a fluid and filter change may be sufficient. If the fluid is dark brown and smells burnt, the transmission has likely suffered internal damage and may need a rebuild.