DTC P0406 (Flash Code 44) EGR Sensor Circuit High (RZ4E-TC)

1. Engine control system check

Refer to "51.Engine Control 1A.Troubleshooting(RZ4E-TC) Diagnostic system check-engine controls".

2. EGR position sensor signal voltage check

1) Connect the scan tool.

2) Turn OFF the ignition switch for 30 seconds or more.

3) Start the engine.

4) Observe the Exhaust Gas Recirculation (EGR) Valve Position parameter on the scan tool. Is the Exhaust Gas Recirculation (EGR) Valve Position parameter more than or equal to the specified value?

Value: 4.9 V

Yes

=>Go to Prioritized DTC and EGR position sensor signal voltage check.

Go to Intermittent conditions of engine.

Refer to "202.Engine 15D.Symptom(RZ4E-TC) intermittent conditions of engine".

3. Prioritized DTC and EGR position sensor signal voltage check

1) Observe the DTC information with a scan tool for DTC P1655 being set at the same time.

2) Turn OFF the ignition switch.

3) Disconnect the EGR valve harness connector (E49).

Refer to "RHD Engine Control (RZ4E)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Refer to "LHD Engine Control (RZ4E)" in the ETM (wiring diagram). (Open using the ETM viewer.).

4) Turn ON the ignition switch.

5) Observe the Exhaust Gas Recirculation (EGR) Valve Position parameter on the scan tool.

Value: 0.1 V

The reading is more than the specified value.

=>Go to Inspection for short to power supply in EGR position sensor signal circuit.

The reading is less than or equal to the specified value and DTC P1655 is set.

Go to DTC P1655 diagnosis.

Refer to "51.Engine Control 1A.Troubleshooting(RZ4E-TC) DTC P1655 (Flash Code 59) Sensor Reference Voltage 4 Circuit".

The reading is less than or equal to the specified value and DTC P1655 is not set.

=>Go to EGR position sensor low reference circuit inspection using test lamp.

4. EGR position sensor low reference circuit inspection using test lamp

1) Connect a test lamp between the EGR position sensor low reference circuit (pin 2 of E49) and the battery power supply. Does the test lamp illuminate?

Refer to "RHD Engine Control (RZ4E)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Refer to "LHD Engine Control (RZ4E)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Yes

=>Go to EGR valve harness connector inspection.

=>Go to Inspection for open circuit in EGR position sensor low reference circuit.

5. Inspection for short to power supply in EGR position sensor signal circuit

1) Inspect the position sensor signal circuit between the ECM (pin 11 of E4) and the EGR valve (pin 3 of E49) for the following. Is the result normal?

Short to the battery power supply circuit or short to the ignition power supply circuit
Short to the 5 V reference circuit

Note

The EGR position sensor may be damaged if the sensor signal circuit is shorted to the power supply.

Refer to "RHD Engine Control (RZ4E)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Refer to "LHD Engine Control (RZ4E)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Yes

=>Go to ECM replacement.

Repair the circuit as necessary.

=>Go to Repair verification.

6. Inspection for open circuit in EGR position sensor low reference circuit

1) Inspect the position sensor low reference circuit between the ECM (pin 28 of E4) and the EGR valve (pin 2 of E49) for an open circuit or high resistance. Is the result normal?

Caution

The EGR position sensor shares the low reference circuit with other sensors. A malfunction in the low reference circuit may set DTCs on sensors that share this circuit.

Refer to "RHD Engine Control (RZ4E)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Refer to "LHD Engine Control (RZ4E)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Yes

=>Go to ECM harness connector inspection.

Repair the circuit as necessary.

=>Go to Repair verification.

7. EGR valve harness connector inspection

1) Inspect for poor connections at the EGR valve harness connector (pin 2 of E49). Is the connection status normal?

Refer to "RHD Engine Control (RZ4E)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Refer to "LHD Engine Control (RZ4E)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Yes

Replace the EGR valve.

Refer to "1.Engine 1H.Aux. Emission Control Devices(RZ4E-TC) EGR removal".

Refer to "1.Engine 1H.Aux. Emission Control Devices(RZ4E-TC) EGR installation".

=>Go to Repair verification.

Repair the connections as necessary.

=>Go to Repair verification.

8. ECM harness connector inspection

1) Inspect for poor connections at the ECM harness connector (pin 28 of E4). Is the connection status normal?

Refer to "RHD Engine Control (RZ4E)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Refer to "LHD Engine Control (RZ4E)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Yes

=>Go to ECM replacement.

Repair the connections as necessary.

=>Go to Repair verification.

9. ECM replacement

Note

Perform programming after replacing the ECM.

Refer to "1.Engine 1Z.Engine Electrical Control(RZ4E-TC) ECM removal".

Refer to "1.Engine 1Z.Engine Electrical Control(RZ4E-TC) ECM installation".

Refer to "1.Engine 1Z.Engine Electrical Control(RZ4E-TC) ECM setting".

Procedure completion

=>Go to Repair verification.

10. Repair verification

1) Clear the DTC with a scan tool.

2) Turn OFF the ignition switch for 30 seconds or more.

3) Start the engine.

4) Operate the vehicle under the conditions for running the DTC.

5) Observe the DTC information with a scan tool.