For 1990-2009 cars

### 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 | Cause | DTCs
--- | --- | ---
DTC P0218 detects a very high transmission fluid temperature (TFT) without a TFT sensor malfunction.
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 air conditioning (A/C) condenser have air flow obstructions and may include a large number of bent fins

• | The cooling fans do not operate

• | Inspect the engine mechanical for worn, leaking, cracked cylinder heads, or engine block

P0116

Transmission | Vehicle Overload or Beyond Towing Capacity:

• | Vehicle is overloaded

• | Vehicle is towing beyond capacity

• | Towing in wrong gear

• | Vehicle modifications

P0218

Heat Transfer:

• | Engine overheating

• | Cooler restrictions - radiator has restricted flow/blockage

• | Restricted air flow

• | Vehicle modifications

• | Aftermarket auxiliary cooler not installed correctly, incorrect flow direction -- reversed flow

• | Restricted, blocked, or pinched transmission cooler lines.

P0218

Transmission Abuse:

• | Engine overheating

• | Excessive brake torque maneuvers

• | Vehicle overloaded

• | Vehicle is towing beyond capacity

• | Vehicle modifications

P0218

Vehicle Damage:

• | Damage to vehicle under carriage

• | Transmission bottom pan damage

• | Restricted air flow

P0218

Transmission Fluid:

• | Fluid leaks

• | Low fluid level

• | Contaminated or poor fluid quality

P0218

Torque Converter:

• | Inefficient pump

• | Torque converter failure -- 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

Transmission fluid is drawn from the bottom pan through the filter, case assembly, channel plate assembly, control valve body assembly, and into the oil pump assembly. The pump is mounted on the control valve body assembly. Fluid pressure leaving the pump is controlled by the pressure regulator valve and becomes the main supply of line pressure to the various components and hydraulic circuits. Hot fluid from the torque converter, the primary source of heat in the transmission, flows through the torque converter clutch (TCC) control valve into the oil cooler supply line. The oil cooler supply line connects to the oil cooler, which is located in the vehicle radiator and auxiliary oil cooler, if equipped. Cool fluid then returns by way of the oil cooler return line to lubricate the final drive assembly and other components along the output shaft. After lubricating the internal components, the oil returns to the oil pan. The TFT sensor, attached to the bottom of the valve body, is part of the internal transmission wire harness and not serviced separately. The normal TFT operating temperature is -40 to +151°C (-40 to +304°F).

### Conditions for Running the DTC

• | The ignition voltage is between 9.0 volts and 19.0 volts.

• | The TFT is -39 to +149°C (-38 to +300°F) for 5 seconds.

### Conditions for Setting the DTC

The TFT is 140°C (284°F) or greater for 1 minute.

### Action Taken When the DTC Sets

• | DTC P0218 is a Type C DTC.

• | The TCM freezes transmission adaptive functions.

### Conditions for Clearing the DTC

DTC P0218 is a Type C DTC.

### Diagnostic Aids

The driver information center (DIC), if equipped, will display 'TRANSMISSION HOT- Idle Engine' when the TFT reaches 132°C (270°F). The TFT on the scan tool should rise steadily to a normal operating temperature, and then stabilize. Ask about the customer's driving habits, trailer towing, etc. Trailer towing should occur in DRIVE (D). Ensure the engine cooling system is functioning normally.

### Reference Information

#### Schematic Reference

Automatic Transmission Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

• | Transmission General Description

• | Transmission Component and System Description

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

Important: Ensure the transmission fluid is at the proper level by performing the Transmission Fluid Check .

1. Ask about the customer driving habits, trailer towing, etc. Trailer towing should occur in D.
2. Review the Failure Records when the DTC set. Verify the engine coolant temperature is less than 125°C (257°F).

⇒ | If greater than the specified value, refer to Engine Overheating .

3. Ensure the engine cooling system is functioning normally/properly. The TFT on the scan tool should rise steadily to a normal operating temperature, and then stabilize.
4. Inspect the transmission cooling system for restrictions or damage.
5. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

### Circuit/System Testing

Important: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

1. Inspect for restricted air flow through the radiator and/or auxiliary cooler, if equipped, due to debris or damaged fins.

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

2. Inspect the transmission cooling system and/or auxiliary cooler, if equipped, for kinked or damaged transmission cooler lines.

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

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

⇒ | 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.

⇒ | if the line pressure is low, refer to Fluid Pressure High or Low .

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Perform the Service Fast Learn Adapts following all transmission related repairs.