PRE-RELEASE
DTC P0117 or P0118 (LAU)
| DTC P0117 or P0118 (LAU) |
| Diagnostic Instructions |
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Perform the
Diagnostic System Check - Vehicle
prior to using this diagnostic procedure.
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Review
Strategy Based Diagnosis
for an overview of the diagnostic approach.
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Diagnostic Procedure Instructions
provides an overview of each diagnostic category.
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| DTC Descriptors |
DTC P0117
Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage
DTC P0118
Engine Coolant Temperature (ECT) Sensor Circuit High Voltage
| Diagnostic Fault Information |
| Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
| ECT Sensor Signal | P0117 | P0118, P0119 | P0118, P0119* | P0116 |
| Low Reference | - | P0118, P0119 | P0118, P0119* | P0116 |
| * Sensor or ECM damage may occur if the circuit is shorted to B+ | ||||
| Typical Scan Tool Data |
ECT Sensor
| Circuit | Short to Ground | Open | Short to Voltage |
| Operating Conditions: Engine operating in Closed Loop. Parameter Normal Range: -39 to +142 °C (-38 to +288 °F). Varies with coolant temperature. | |||
| ECT Sensor Signal | 143°C (289°F) | -40°C (-40°F) | -40°C (-40°F)* |
| Low Reference | - | -40°C (-40°F) | -40°C (-40°F)* |
| * Internal ECM or ECT sensor damage may occur if the circuit is shorted to B+ | |||
| Circuit Description |
The engine coolant temperature (ECT) sensor is a variable resistor that measures the temperature of the engine coolant. The engine control module (ECM) supplies 5 V to the ECT signal circuit and supplies a ground to the low reference circuit.
The following table illustrates the difference between temperature, resistance, and voltage:
| ECT | ECT Resistance | ECT Signal Voltage |
| Cold | High | High |
| Warm | Low | Low |
| Conditions for Running the DTC |
P0117
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The engine is operating.
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DTCs P0116, P0118, or P0119 are not set.
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The start up intake air temperature (IAT) is less than 75°C (167°F).
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The difference between intake temperature (IAT) and intake air temperature at last engine shut down is less than 20°C (70°F).
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The engine run time is greater than 60 s.
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The DTC runs continuously once the above conditions are met.
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P0118
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The engine is operating.
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DTCs P0116, P0117 or P0119 are not set.
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The start up intake air temperature (IAT) is less than 75°C (167°F).
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The difference between intake temperature (IAT) and intake air temperature at last engine shut down is less than 20°C (70°F).
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The DTC runs continuously once the above condition is met.
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| Conditions for Setting the DTC |
P0117
The ECM detects that the ECT is greater than 140°C (284°F) for greater than 1 s or a cumulative of 10 s.P0118
The ECM detects that the ECT is less than -39°C (-38°F) for greater than 1 s or a cumulative of 10 s.| Action Taken When the DTC Sets |
DTC P0117 and P0118 are Type B DTCs.
| Conditions for Clearing the MIL/DTC |
DTC P0117 and P0118 are Type B DTCs.
| Diagnostic Aids |
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Test the ECT sensor at various temperature levels in order to evaluate the possibility of a skewed sensor. A skewed sensor can result in a DTC or a driveability condition. Refer to
Temperature Versus Resistance - Engine Coolant Temperature Sensor
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If the vehicle has sat overnight, the IAT sensor and the ECT sensor values should display within 3°C (5°F).
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After starting a cold engine, the ECT sensor temperature should rise steadily, then stabilize after the thermostat opens.
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High resistance in the circuits of either the ECT or IAT sensor could set a DTC.
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| Reference Information |
Schematic Reference
Engine Controls Schematics (3.0L (LF1)) Engine Controls Schematics (2.8L (LAU))
Connector End View Reference
Component Connector End Views
Electrical Information Reference
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Circuit Testing
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Connector Repairs
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Testing for Intermittent Conditions and Poor Connections
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Wiring Repairs
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DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
| Circuit/System Verification |
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Engine idling for 1 min. Check the DTC information with a diagnostic tool. DTCs P0117 and P0118 should not set.
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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.
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| Circuit/System Testing |
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Ignition OFF, disconnect the harness connector at the B34 ECT sensor.
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Test for less than 5 Ω between the low reference circuit terminal 2 and ground. |
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Warning
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If greater than the specified range, test the low reference circuit for an open/high resistance, or for a short to voltage. If the circuit tests normal, replace the K20 ECM.
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Ignition ON, verify that the scan tool ECT sensor parameter is at -40°C (-40°F).
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If greater than the specified range, test the signal circuit's pin 1 for a short to ground. If the circuit tests normal, replace the K20 ECM.
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Ignition ON, install a 3 A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2. Verify the ECT sensor parameter is greater than 142°C (288°F). |
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If less than the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
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If all circuits test normal, test or replace the B34 ECT sensor.
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| Component Testing |
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Ignition OFF, disconnect the harness connector at the B34 engine coolant temperature (ECT) sensor.
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Test the ECT sensor by varying the sensor temperature while monitoring the sensor resistance. Compare the readings with the Temperature Versus Resistance - Engine Coolant Temperature Sensor table and verify that the resistance is within 5 % of the specification. |
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If not within the specified range, replace the B34 ECT sensor.
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| Repair Instructions |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
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Engine Coolant Temperature Sensor Replacement (LAU)
Engine Coolant Temperature Sensor Replacement (LF1)
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Control Module References
for ECM replacement, setup, and programming
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