Diagnostic Instructions

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	Review Strategy Based Diagnosis for an overview of the diagnostic approach.

•	Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P0218

Transmission Fluid Overtemperature

Diagnostic Fault Information

Component	Condition	DTCs
Engine	• Engine coolant level low • Incorrect engine coolant • Old coolant or incorrect concentration level • Cooling system leak • Radiator hose kinked or pinched • Loose, missing, or damaged radiator air seals or deflector poor air flow • The radiator and A/C condenser has air flow obstructions to include large amount of bent fins. • The cooling fans do not operate. • Inspect the engine mechanical for worn, leaking, cracked cylinder heads, or engine block.	P0218
Transmission	Vehicle Overload or Beyond Capacity Towing: • Vehicle is overloaded • Vehicle is towing beyond capacity • Towing in wrong gear • Towing in wrong gear	P0218
	Heat Transfer: • Engine Overheating • Cooler restrictions - radiator has restricted flow/blockage • Restricted air flow • Vehicle modifications • Aftermarket auxiliary cooler installed incorrectly, incorrect flow direction - reversed flow • Restricted, blocked, or pinched transmission cooler lines	P0218
	Transmission Abuse: • Engine Overheating • Vehicle is overloaded • Vehicle is towing beyond capacity • Vehicle modifications	P0218
	Transmission Fluid: • Fluid leaks • Low fluid level • Contaminated or poor fluid quality	P0218
	Torque Converter: • Inefficient pump • Torque converter inoperative or affected - stator, pump, clutch, ballooning or heat damaged • Stuck on or locked up • Converter damage	P0218
	Low Pump Output: • Low fluid level • Blocked, damaged or loose filter • Pinched or restricted cooler lines • Restricted cooler - damage or debris • Inefficient pump - worn	P0218
	Clutch Slippage: • Low fluid level • Low Pump Output	P0218

Circuit/System Description

The primary source of heat in the transmission is the torque converter. Hot oil exits the torque converter through the torque converter clutch (TCC) control valve and flows to the transmission cooler supply line. The supply line connects to the cooler, which is in the radiator. From the cooler, the oil returns through the oil cooler return line and enters the lubrication circuits. After lubricating the internal components, the oil returns to the oil pan. The transmission fluid temperature sensor is located in the control solenoid valve assembly.

Conditions for Running the DTC

•	The ignition voltage is between 10.2-15.5 V.

•	The engine speed is greater than 400 RPM for 2 s.

•	The transmission is not in emergency mode.

•	Transmission control module (TCM) communication is normal.

Conditions for Setting the DTC

•	Vehicle speed less than 180 km/h (112 MPH) and transmission fluid temperature more than 150°C (302°F) for more than 10 s

•	Vehicle speed more than 180 km/h (112 MPH) and transmission fluid temperature more than 150°C (302°F) for more than 60 s

Action Taken When the DTC Sets

•	DTC P0218 is a Type C DTC.

•	Warning message to the driver via CAN bus

Conditions for Clearing the DTC

•	DTC P0218 is a Type C DTC.

•	Vehicle speed less than 170 km/h (106 MPH) and transmission fluid temperature less than 140°C (284°F) for more than 3 s

•	Vehicle speed more than 170 km/h (106 MPH) and transmission fluid temperature less than 140°C (284°F) for more than 3 s

Diagnostic Aids

Ask the customer whether their typical day-to-day driving include:

•	Trailer towing

•	Trailer towing should occur in D 4th gear.

•	Hauling or vehicle overloading

•	Hot climate driving

•	Extended idling

•	Extreme off-road conditions

•	Ensure the engine cooling system is functioning normally.

Reference Information

Schematic Reference

Automatic Transmission Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

Description and Operation

•	Transmission Indicators and Messages

•	Transmission Component and System Description

•	Transmission Overheats

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1.	Verify the transmission fluid level, color and odor is correct.

2.	Review the Freeze Frame when the DTC set.

3.	If the engine coolant temperature (ECT) was above 125°C (257°F) when the DTC set, refer to Engine Overheating and correct that concern first.

Circuit/System Testing

Dynamic Test

1.	Inspect the transmission cooling system for restrictions or damage, inducing any auxiliary cooler if equipped.

2.	Perform the Transmission Fluid Cooler Flushing and Flow Test to verify proper transmission oil cooler flow.

3.	If a concern is found, repair or replace the damaged components as necessary.

4.	Perform the Line Pressure Check to verify proper transmission line pressure.

5.	If a concern is found, repair or replace the damaged components as necessary.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Transmission Fluid Level and Condition Check

•	Transmission Fluid Cooler Hose/Pipe Quick-Connect Fitting Disconnection and Connection

•	Control valve body-Refer to Control Valve Body Replacement.

•	TCM-Refer to Control Module References.

•	Perform the Transmission Adaptive Functions.