DTC P1446, P1447, P244C, or P244D. Holden Epica 2007

For 1990-2009 cars only

Makes 🢒 Holden 🢒 2007 🢒 Epica 🢒 DTC 🢒 DTC P1446, P1447, P244C, or P244D

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 P1446: Pre-Catalyst Temperature Too Low During Regeneration

DTC P1447: Pre-Catalyst Temperature Too High During Regeneration

DTC P244C: Catalyst Temperature Too Low During Regeneration

DTC P244D: Catalyst Temperature Too High During Regeneration

Circuit/System Description

The diesel exhaust after-treatment system consists of an under hood pre-catalytic converter and an underbody catalytic converter. The underbody catalytic converter also consists of the main Diesel Oxidation Catalyst (DOC) and the coated Diesel Particulate Filter (DPF). One of the main purposes of the DPF is to collect particulates from the engine exhaust in order to minimize discharge of soot to the atmosphere. The soot particles accumulate in the channels of the DPF and are burned off at regular intervals through a process called regeneration. This prevents the DPF from clogging. The ECM commands the DPF regeneration after calculating various vehicle conditions such as DPF pressure difference, exhaust gas temperature, engine oil quality, engine speed, etc. Excessive accumulation of the soot in the DPF can cause a drop in the engine performance. During regeneration, additional fuel is injected via multiple post injections in order to increase the exhaust gas temperature. During this period, the DPF temperature is raised to approximately 600°C and the accumulated soot is oxidized or burned off into carbon-dioxide (CO2).

Conditions for Running the DTC

The DTC runs during the DPF regeneration process.

Conditions for Setting the DTC

P1446

The actual temperature of the exhaust gas temperature (EGT) sensor 1 is 200°C (392°F) less than the desired temperature.

DTC P1447

The actual temperature of the exhaust gas temperature (EGT) sensor 1 is 100°C (212°F) greater than the desired temperature.

P244C

The actual temperature of the exhaust gas temperature (EGT) sensor 2 is 125°C (257°F) less than the desired temperature.

P244D

The actual temperature of the exhaust gas temperature (EGT) sensor 2 is 150°C (302°F) greater than the desired temperature.

Action Taken When the DTC Sets

DTCs P1446, P1447, P244C, and P244D are type A DTCs.

Conditions for Clearing the DTC

DTCs P1446, P1447, P244C, and P244D are type A DTCs.

Diagnostic Aids

•	If the engine has sat overnight, both EGT sensors and the ECT sensor values should display within 3°C (5°F).

•	After starting a cold engine, the EGT sensors temperature should rise steadily, then stabilize.

•	High resistance in the circuits of either of the EGT sensors could set a DTC.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

•	Engine Control Module Connector End Views

•	Engine Controls Connector End Views

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

•	Scan Tool Data List

•	Scan Tool Data Definitions

•	Scan Tool Output Controls

Circuit/System Verification

Ignition On, observe the diagnostic trouble code (DTC) information with a scan tool. Verify no other DTCs are set.

⇒	If any other DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.

Engine idling, perform a regeneration procedure with a scan tool. Observe the DTC information with a scan tool. DTCs P1446, P1447, P244C, and P244D should not set.
Operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records List.

Circuit/System Testing

Ignition OFF, and the MAIN fuse removed, disconnect the harness connector at the appropriate EGT sensor.
Test for less than 5 ohms of resistance between the low reference circuit terminal 2 and ground.

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit/connections test normal, replace the ECM.

Install the MAIN fuse. Ignition ON, verify that the scan tool EGT sensor parameter is at 5 volts.

⇒	If less than the specified value, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.

Important: If the fuse in the jumper wire opens, the signal circuit is shorted to a voltage and the sensor may be damaged.

Install a 1A fused jumper wire between the signal circuit terminal 1 and ground. Verify the scan tool EGT sensor parameter is at 0 volts.

⇒	If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

Inspect for the following conditions:

•	Intake and exhaust system for leaks or restrictions

•	Fuel system for leaks or restrictions

•	Excessive water in fuel

•	EGR for normal operation

•	Plugged fuel filter

•	Restricted air filter

•	Turbocharger operation

•	An engine mechanical condition

⇒	If a condition is found, repair as necessary.

If all circuits/components test normal, replace the EGT sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Exhaust Gas Temperature (EGT) Sensor Replacement.

•	Control Module References for ECM replacement, programming and setup.

Repair Verification

Ignition ON, observe the scan tool DPF soot mass parameter. The parameter should be less than 24 grams.

⇒	If greater than the specified range, perform a DPF service regeneration. Refer to Exhaust Particulate Filter Cleaning .