GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2008 🢒 Canyon Pickup - 2WD 🢒 Power and Signal Distribution 🢒 Wiring Systems and Power Management 🢒 DTC P0218

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

Circuit/System Description

The flow of transmission fluid starts in the bottom pan and is drawn through the filter, control valve body assembly, transmission case and into the oil pump assembly. The oil pump assembly pressurizes the fluid and directs it to the pressure regulator valve where it becomes the main supply of fluid to the various components and hydraulic circuits in the transmission. Hot fluid exiting the torque converter flows through the converter clutch apply valve and into the transmission cooler lines to the oil cooler located in the vehicle radiator, and auxiliary cooler if equipped. From the cooler, fluid returns to cool and lubricate the front of the transmission. In forward drive ranges, D4 fluid from the manual valve is routed through an orificed cup plug in the rear of the transmission case to feed the rear lube fluid circuit.

Conditions for Running the DTC

The transmission fluid temperature is between -39 and +149°C (-38 and +300°F) for 5 seconds.

Conditions for Setting the DTC

The transmission fluid temperature is 136°C (277°F) or greater for 60 seconds.

Action Taken When the DTC Sets
    • DTC P0218 is a Type C DTC.
    • TRANS HOT - IDLE ENGINE displays on the driver information center (DIC).
    • The transmission control module (TCM) freezes transmission adaptive functions.

Conditions for Clearing the DTC

DTC P0218 is a Type C DTC.

Diagnostic Aids
    • The DIC, if equipped, will display TRANS HOT - IDLE ENGINE when the transmission fluid temperature reaches 132°C (270°F).
    • Ask the customer about possible overloading, exceeding the trailer towing limit, or towing in overdrive.
    • Refer to Symptoms - Automatic Transmission .

Reference Information

Schematic Reference

Automatic Transmission Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Transmission General Information

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

Transmission Control Module Scan Tool Information

Circuit/System Verification

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

Circuit/System Testing

Inspect for the following conditions:

    • Transmission line pressure low--Refer to Line Pressure Check . If the line pressure is low, refer to Oil Pressure High or Low .
    • Transmission fluid flow through cooler and/or auxiliary cooler, if equipped, is restricted due to:
       - Transmission fluid level low
       - A clogged filter
       - A leaking filter or seal--Refer to Automatic Transmission Fluid and Filter Replacement .
    • A seized stator in the torque converter--Refer to Torque Converter Diagnosis .
    • Air flow through transmission fluid cooler and/or auxiliary cooler, if equipped, is restricted due to:
       - Damaged fins
       - Debris
    • Engine overheating due to:
       - Low coolant level--Check coolant temperature, coolant level, and hoses.
       - Restricted air flow
       - Restricted coolant flow--Refer to Engine Overheating
⇒If any of the conditions listed are found, repair as necessary.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.