DTC P0234 (Flash Code 42) Turbocharger Overboost Condition (RZ4E-TC)

Note

Observe that the boost pressure sensor signal is normal with a scan tool. Compare the Boost Pressure with the Desired Boost Pressure under all load conditions, and observe whether an excessively high value is displayed.
If there is gasoline entered into fuel, this DTC may be set.

1. Engine control system check

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

2. Prioritized DTC check

1) Connect the scan tool.

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

3) Start the engine.

4) Observe the DTC information with a scan tool. Is DTC P0047, P0237, P0238, P0638, P2227, P2228, or P2229 set at the same time?

Yes

Go to the applicable DTC diagnosis.

Refer to "51.Engine Control 1A.Troubleshooting(RZ4E-TC) DTC P0047 (Flash Code 249) Turbocharger Boost Control Solenoid Circuit".

Refer to "51.Engine Control 1A.Troubleshooting(RZ4E-TC) DTC P0237 (Flash Code 32) Turbocharger Boost Sensor Circuit Low".

Refer to "51.Engine Control 1A.Troubleshooting(RZ4E-TC) DTC P0238 (Flash Code 32) Turbocharger Boost Sensor Circuit High".

Refer to "51.Engine Control 1A.Troubleshooting(RZ4E-TC) DTC P0638 (Flash Code 61) Throttle Actuator Control Range/Performance".

Refer to "51.Engine Control 1A.Troubleshooting(RZ4E-TC) DTC P2227 (Flash Code 71) Barometric Pressure Circuit Range/Performance".

Refer to "51.Engine Control 1A.Troubleshooting(RZ4E-TC) DTC P2228 (Flash Code 71) Barometric Pressure Circuit Low".

Refer to "51.Engine Control 1A.Troubleshooting(RZ4E-TC) DTC P2229 (Flash Code 71) Barometric Pressure Circuit High".

=>Go to Pressure difference check between the boost pressure and the barometric pressure.

3. Pressure difference check between the boost pressure and the barometric pressure

1) Turn ON the ignition switch.

2) Observe the Boost Pressure parameter and Barometric Pressure (BARO) parameter on the scan tool. Is the difference between the Boost Pressure parameter and the Barometric Pressure (BARO) parameter more than or equal to the specified value?

Note

If the Boost Pressure parameter on the scan tool shows a value close to the barometric pressure while the ignition switch is ON with the engine stopped, it is considered normal.

Value: 10 kPa { 1.5 psi }

Yes

=>Go to Barometric pressure check.

=>Go to Mechanical parts inspection.

4. Barometric pressure check

1) Refer to the table and compare the Barometric Pressure (BARO) parameter on the scan tool with the surrounding barometric pressure. Is the Barometric Pressure (BARO) parameter within the specified range?

Refer to "1.Engine 1Z.Engine Electrical Control(RZ4E-TC) barometric pressure sensor inspection".

Yes

=>Go to Boost pressure sensor circuit inspection.

=>Go to Barometric pressure sensor circuit inspection.

5. Mechanical parts inspection

1) Inspect possible causes of the high boost pressure for the following. Is the result normal?

Incorrect installation, disconnection, or twisting of the turbocharger control actuator vacuum hose
Stuck turbocharger control actuator or turbocharger control solenoid valve.
Stuck intake throttle valve
Oil in the air intake pipe may cause a boost pressure sensor signal error. If there is oil inside the piping, intercooler, or turbocharger, it is necessary to wipe it off.

Yes

Go to Intermittent conditions of engine.

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

Repair or replace as necessary.

=>Go to Repair verification.

6. Boost pressure sensor circuit inspection

1) Inspect for poor connections at the boost pressure and CAC temperature sensor harness connector (pin 2 of E51). Is the connection status normal?

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

3) Inspect the boost pressure sensor low reference circuit between the ECM (pin 28 of E4) and the boost pressure and CAC temperature sensor (pin 2 of E51) for high resistance. Is the result 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.).

4) Are all of the results normal?

Yes

Replace the boost pressure and CAC temperature sensor.

Refer to "1.Engine 1Z.Engine Electrical Control(RZ4E-TC) boost pressure and CAC temperature sensor removal".

Refer to "1.Engine 1Z.Engine Electrical Control(RZ4E-TC) boost pressure and CAC temperature sensor installation".

=>Go to Repair verification.

Repair the circuit or connection as necessary.

=>Go to Repair verification.

7. Barometric pressure sensor circuit inspection

1) Inspect for poor connections at the barometric pressure sensor harness connector (pins 2 and 3 of C37). Is the connection status normal?

2) Inspect for poor connections at the ECM harness connector (pins 61 and 71 of C7). Is the connection status normal?

3) Inspect the circuit between the ECM (pins 61 and 71 of C7) and the barometric pressure sensor (pins 2 and 3 of C37) for high resistance. Is the result 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.).

4) Are all of the results normal?

Yes

Replace the barometric pressure sensor.

Refer to "1.Engine 1Z.Engine Electrical Control(RZ4E-TC) barometric pressure sensor removal".

Refer to "1.Engine 1Z.Engine Electrical Control(RZ4E-TC) barometric pressure sensor installation".

=>Go to Repair verification.

Repair the circuit or connection as necessary.

=>Go to Repair verification.

8. 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.