DTC P0234 Turbocharger / Supercharger Overboost Condition
DTC P0299 Turbocharger / Supercharger Underboost
DTC P1251 Turbocharger / Supercharger Overboost Condition (Too High)
Description
Toyota fault code list DTC P0234 DTC P0299 DTC P1251 2AD-FHV
DTC No. | DTC Detection Condition | Trouble Area |
P0234 P0299 P1251 |
When the turbocharger pressure exceeds the standard value for 0.5 seconds or more (1 trip detection logic) |
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Actual turbocharger pressure is deviated 20 kPa (150 mmHg, 5.9 in.Hg) or more from the simulated target pressure for 60 seconds (1 trip detection logic) |
Wiring diagram

Inspection procedure
NOTICE:
After replacing the ECM, the new ECM needs registration and initialization.
1.CHECK OTHER DTC OUTPUT (IN ADDITION TO DTC P0234, P0299 AND/OR P1251) |
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Connect the intelligent tester to the DLC3.
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Turn the ignition switch on (IG) and turn the tester ON.
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Enter the following menus: Powertrain / Engine and ECT / DTC.
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Read DTCs.
Result:Display (DTC Output) Proceed to P0234, P0299 and/or P1251 A P0234, P0299 and/or P1251 and other DTCs B
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A | |
2.CHECK CONNECTION OF VACUUM HOSE |
HINT:
Check the vacuum hoses of turbocharger system connections.
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OK | |
3.CHECK VACUUM (TURBOCHARGER - VRV FOR TURBOCHARGER CONTROL) |
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Using a three-way connector, connect a vacuum gauge to the hose between the VRV and turbocharger.
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Warm up the engine coolant temperature to above 75°C (167°F).
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Check the vacuum at the engine speed of 900 rpm.
Result:Vacuum Proceed to 0 kPa (0 mmHg, 0 in.Hg) to 50 kPa (375 mmHg, 14.8 in.Hg) A Above 50 kPa (375 mmHg, 14.8 in.Hg) B
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A | |
4.INSPECT VRV FOR TURBOCHARGER CONTROL (VRV RESISTANCE) |
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Measure the VRV resistance.
Standard resistance:
11.1 to 12.5 ?
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OK | |
5.CHECK WIRE HARNESS (VRV FOR TURBOCHARGER CONTROL - ECM) |
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Disconnect the B44 VRV connector.
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Disconnect the B32 ECM connector.
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Measure the resistance of the wire harness side connectors.
Standard resistance:
Tester Connection Specified Condition B32-84 (VN) - B44-2 Below 1 ? B32-84 (VN) or B44-2 - Body ground 10 k? or higher -
Reconnect the VRV connector.
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Reconnect the ECM connector.
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OK | |
6.INSPECT TURBOCHARGER SUB-ASSEMBLY |
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Check the turbocharger sub-assembly.
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OK | |
7.INSPECT EGR VALVE ASSEMBLY |
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Check the EGR valve assembly.
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OK | |
8.READ VALUE OF MANIFOLD ABSOLUTE PRESSURE SENSOR |
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Connect the intelligent tester to the DLC3.
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Turn the ignition switch on (IG) and turn the tester ON.
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Enter the following menus: Powertrain / Engine and ECT / Data List / MAP and Atmosphere Pressure.
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Read the value.
OK:
Condition MAP Value No pressure applied Same as atmospheric pressure Vacuum applied Becomes vacuum Pressure applied Becomes pressurized
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OK | |
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