DTC Advanced Diagnostics: P0234
DTC P0234:Turbocharger Overboost Problem

General Description


The powertrain control module (PCM) controls the turbocharger boost pressure so that the boost pressure to the engine does not exceed the set upper pressure limit. When the boost pressure increases abnormally, a malfunction of the turbocharger control system is determined and fuel cut and throttle restriction control is done to protect the powertrain.

Monitor Execution, Sequence, Duration, DTC Type
Execution
Continuous
Sequence
None
Duration
1.0 second or more
DTC Type
One drive cycle, MIL on

Enable Conditions
Condition
Minimum
Maximum
Engine coolant temperature
[ECT SENSOR 1]
156 °F (69 °C)
–
Engine speed
[ENGINE SPEED]
1,000 rpm
–
Other
No change of boost pressure upper limit
[ ]: HDS Parameter

Malfunction Threshold
Either one of conditions is met for at least 1.0 second, and fuel cut-off is operated for engine protection.
The boost pressure is 148 - 300 kPa (1,109 - 2,250 mmHg, 43.7 - 88.6 inHg) or more*
The intake air pressure is 260 - 292 kPa (1,948 - 2,192 mmHg, 76.8 - 86.3 inHg) or more*

*: Varies with driving conditions.

Possible Cause
NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes
Turbocharger wastegate control valve stuck close failure
Turbocharger wastegate control actuator stuck close failure
Turbocharger wastegate control valve bypass clogged
PCM internal circuit failure (BARO sensor)
Turbocharger boost sensor internal failure

Confirmation Procedure
Operating Condition
1.
Start the engine. Hold the engine speed [ENGINE SPEED] at 3,000 rpm without load (in neutral) until the radiator fan comes on.
2.
Drive at engine speed [ENGINE SPEED] at 1,200 rpm or more for at least 1 second.
Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.
With the HDS
None.

Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected, the MIL comes on and a Pending DTC, a Confirmed DTC, and the freeze data are stored in the PCM memory.

Conditions for clearing the DTC
The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the 12 volt battery.