DTC P0234 Turbocharger Overboost Condition (4JJ3 without DPD)

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(4JJ3 without DPD) Diagnostic system check-engine controls".

2. Prioritized DTC check

1) Connect the scan tool.

2) Turn OFF the ignition switch for 1 minute or more.

3) Start the engine.

4) Observe the DTC information with a scan tool. Is DTC 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(4JJ3 without DPD) DTC P0237 Turbocharger Boost Sensor Circuit Low".

Refer to "51.Engine Control 1A.Troubleshooting(4JJ3 without DPD) DTC P0238 Turbocharger Boost Sensor Circuit High".

Refer to "51.Engine Control 1A.Troubleshooting(4JJ3 without DPD) DTC P0638 Throttle Actuator Control Range/Performance".

Refer to "51.Engine Control 1A.Troubleshooting(4JJ3 without DPD) DTC P2227 Barometric Pressure Circuit Range/Performance".

Refer to "51.Engine Control 1A.Troubleshooting(4JJ3 without DPD) DTC P2228 Barometric Pressure Circuit Low".

Refer to "51.Engine Control 1A.Troubleshooting(4JJ3 without DPD) DTC P2229 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(4JJ3 without DPD) ECM inspection".

Yes

=>Go to Boost pressure sensor circuit inspection.

=>Go to ECM replacement.

5. Mechanical parts inspection

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

Stuck VGS actuator
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(4JJ3 without DPD) 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 sensor harness connector (pin 2 of E31). Is the connection status normal?

2) Inspect for poor connections at the ECM harness connector (pin 27 of E2). Is the connection status normal?

3) Inspect the low reference circuit between the ECM (pin 27 of E2) and the boost pressure sensor (pin 2 of E31) for high resistance. Is the result normal?

Refer to "LHD Engine Control (4JJ3 without DPD)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Refer to "RHD Engine Control (4JJ3 without DPD)" in the ETM (wiring diagram). (Open using the ETM viewer.).

4) Are all of the results normal?

Yes

Replace the boost pressure sensor.

Refer to "1.Engine 1Z.Engine Electrical Control(4JJ3 without DPD) boost pressure sensor removal".

Refer to "1.Engine 1Z.Engine Electrical Control(4JJ3 without DPD) boost pressure sensor installation".

=>Go to Repair verification.

Repair the circuit or connection as necessary.

=>Go to Repair verification.