P20E2

DTC P20E2

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 provide an overview of each diagnostic category.

DTC Descriptor

DTC 20E2
- Exhaust Temperature Sensor 1-2 Correlation

Diagnostic Fault Information






Typical Scan Tool Data










Circuit/System Description

The exhaust gas temperature sensors are variable resistors that measure the temperature of the exhaust gas at the inlet and outlet of the diesel particulate filter (DPF). The engine control module (ECM) supplies a bias 5-volt signal to the EGT signal circuit, and supplies a ground to the low reference circuit. When the EGT sensor is cold, the sensor resistance is low. When the EGT temperature increases, the sensor resistance increases. With high sensor resistance, the ECM detects a higher voltage on the EGT signal circuit. With lower sensor resistance, the ECM detects a lower voltage on the EGT signal circuit.

Conditions for Running the DTC

* DTCs P0545, P0546, P2032, P2033 are not set.
* The engine has been OFF for greater than 5 hours.
* The engine is running.
* The ambient temperature is greater than 10°C (50°F).
* DTC P20E2 runs once per key cycle within the above enabling conditions.

Conditions for Setting the DTC

* The ECM detects a temperature difference greater than 20°C (68°F) between exhaust temperature sensors - positions 1 and 2.
* This DTC runs once per key cycle when the above condition is met.

Action Taken When the DTC Sets

DTC P20E2 is a Type B DTC.

Conditions for Clearing the DTC

DTC P20E2 is a Type B DTC.

Diagnostic Aids

* A slight to moderate resistance in either signal or low reference circuit, can widen the spread between the two EGT sensors, and cause this DTC to set.
* An EGT sensor that is skewed lower at various ambient temperatures, due to more resistance than is normal, can widen the spread between the two sensors and cause this DTC to set. Measure and record the resistance of both EGT sensors 1 and 2 at ambient temperature. Compare those measurements to the Temperature Versus Resistance (Exhaust Gas Temperature Sensor) Temperature Versus Resistance (Fuel Temperature Sensor) Temperature Versus Resistance (IAT Sensor 1) Temperature Versus Resistance (ECT Sensors) Temperature Versus Resistance (IAT Sensor 2).


Circuit/System Verification

Important: Determine the ambient temperature by using an accurate thermometer.

* If the ignition has been OFF for greater than 5 hours, determine which EGT sensor is skewed by comparing EGT Sensor 1 and 2 parameters to the ambient temperature with a scan tool. The readings should be within 19°C (66°F) of each other and also the ambient temperature.
* Ignition ON, observe the scan tool EGT Sensor 1 and 2 parameters. The readings should be between -40°C to +999°C (-38°F to +1,830°F) depending on the current ambient temperature and the vehicle operating conditions
* Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame Records data.

Circuit/System Testing

1. Ignition OFF, disconnect both harness connectors at EGT sensor 1 and sensor 2.
2. Ignition OFF for 90 seconds, Measure for a resistance of less than 5 ohms on each low reference circuit between terminals B and ground.

• If the resistance is greater than the specified range, repair the open/high resistance on the affected circuit. If the circuit tests normal, replace the ECM.

3. Ignition OFF, disconnect the harness connector X1 at the ECM.
4. Test for less than 5 ohms of resistance on each of the following signal circuits:

* ECM X1 signal circuit terminal 69 to EGT sensor 1 terminal A
* ECM X1 signal circuit terminal 93 to EGT sensor 2 terminal A

• If the resistance is greater than the specified range, repair the open/high resistance on the affected circuit.

5. If all circuits test normal, remove and test each sensor.

Component Testing

Measure and record the resistance of exhaust gas temperature (EGT) sensor 1 and sensor 2 and compare those measurements to the Temperature Versus Resistance (Exhaust Gas Temperature Sensor) Temperature Versus Resistance (Fuel Temperature Sensor) Temperature Versus Resistance (IAT Sensor 1) Temperature Versus Resistance (ECT Sensors) Temperature Versus Resistance (IAT Sensor 2).

Repair Instructions

Notice: After performing the system repair, perform the following:

* A code clear with a scan tool, regardless of whether or not a DTC is set
* A Diesel Particulate Filter (DPF) Regeneration Enable with a scan tool

Perform the above to avoid possible soot overloading conditions or possible damage to DPF.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

* Exhaust Particulate Filter Cleaning (DPF Service Regeneration) Exhaust Particulate Filter Cleaning (DPF Regeneration Enable) for Regeneration Enable
* Exhaust Temperature Sensor Replacement - Position 1
* Exhaust Temperature Sensor Replacement - Position 2
* Engine Control Module Replacement Verification Tests