DTC P0238 Without RPO CTF
Circuit Description
The boost pressure sensor is fixed on the intake manifold and is connected to the intake manifold by a vacuum hose.
The boost pressure sensor generates voltage according to air pressure in the intake manifold and the generated voltage is input to the engine control module (ECM) for the boost sensor signal.
The ECM monitors the boost pressure sensor signals for voltage outside the normal range of the boost pressure sensor. If the ECM detects a boost pressure sensor signal voltage that is excessively low DTC P0237 will set. If the ECM detects a boost pressure sensor signal voltage that is excessively high DTC P0238 will set .
Conditions for Setting the DTC
When the engine stalls and the relative boost pressure is higher than 20 kPa (2.9 psi) for 1 second or more.
Action Taken When the DTC Sets
Condition for setting the DTC Injection amount map is used for a fail-safe mode.
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
Inspect for the following conditions:
| • | Poor connection at the ECM |
| Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connection. |
| • | Damaged harness |
| Inspect the wiring harness for damage, shorts to ground, shorts to battery, and open circuits. If the harness appears to be OK, observe the boost pressure display on the scan tool while moving connectors and wiring harnesses related to the boost pressure sensor. A change in the boost pressure scan tool display will indicate the location of the fault. |
| • | Lack of power due to injection limitation. |
Pressure | Voltage (V) |
|---|---|
67 kPa (9.7psi) | 0.5 V |
200 kPa (29 psi) | 2.5 V |
333 kPa (48 psi) | 4.5 V |
Step | Action | Value | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||
1 | Does the DTC set with the ignition ON or the engine is running? | -- | Go to Step 2 | Go to Intermittent Conditions | ||||
2 |
Does the voltage measure near the specified value? | 1.3 V | Go to Step 8 | Go to Step 3 | ||||
3 | Measure voltage between pin number C4-5 and pin number C4-15 of the ECM harness connector. Does the voltage measure within the specified range? | 4.75-5.25 V | Go to Step 6 | Go to Step 4 | ||||
4 |
Does each resistance measure less than the specified value? | 0.5 ohms | Go to Step 5 | Go to Step 12 | ||||
5 | Measure the resistance of the following points on the boost sensor harness:
Does each resistance measure more than the specified value? | 10 M ohms | Go to Step 11 | Go to Step 12 | ||||
6 |
Does each resistance measure less than the specified value? | 0.5 ohms | Go to Step 7 | Go to Step 12 | ||||
7 | Measure resistance between the following points on the boost sensor harness:
Does each resistance measure more than the specified value? | 10 M ohms | Go to Step 11 | Go to Step 12 | ||||
8 |
Is voltage created to meet boost pressure? | -- | Go to Step 9 | Go to Step 11 | ||||
9 |
Are there any abnormal boost pressure voltages or any leakage? | -- | Go to Step 10 | Go to Step 13 | ||||
10 | Inspect the turbocharger condition, waste gate opening pressure, and/or piping. Is the opening pressure of the waste gate correct? | Go to Step 17 | Go to Step 15 | |||||
11 | Replace the boost pressure sensor. Did you complete the replacement? | -- | Go to Step 13 | -- | ||||
12 | Repair the boost pressure sensor wiring harness. Did you complete the repair? | -- | Go to Step 13 | -- | ||||
13 | Clear all DTCs. Does the DTC reset? | -- | Go to Step 14 | Go to Step 17 | ||||
14 | Replace the ECM. Did you complete the replacement? | Go to Step 16 | -- | |||||
15 | Repair piping and/or readjust the waste gate opening pressure. Did you complete the repair? | -- | Go to Step 16 | -- | ||||
16 |
Does the DTC reset? | -- | Go to Step 2 | Go to Step 17 | ||||
17 | Do any other DTCs set? | -- | System OK | |||||
DTC P0238 With RPO CTF
Circuit Description
The boost pressure sensor is fixed on the intake manifold. The boost pressure sensor generates voltage according to air pressure in the intake manifold, and the generated voltage is input to the engine control module (ECM) as the boost sensor signal. The boost pressure sensor has the following circuits:
| • | A 5-volt reference circuit |
| • | A low reference circuit |
| • | A boost pressure sensor signal circuit |
The ECM supplies 5 volts to the boost pressure sensor on the 5-volt reference circuit. The ECM also provides a ground on the low reference circuit. The boost pressure sensor provides a signal to the ECM on the boost pressure signal circuit which is relative to the pressure changes in the manifold. The ECM should detect a low signal voltage at a low boost pressure, such as low engine load. The ECM should detect high signal voltage at a high boost pressure, such as high engine load. The ECM monitors the boost pressure sensor signals for voltage outside the normal range of the boost pressure sensor. If the ECM detects an excessively high boost pressure sensor signal voltage, this DTC will set.
Conditions for Running the DTC
| • | The ignition switch is ON. |
| • | The battery voltage is between 10-16 volts. |
| • | The engine is not running. |
Conditions for Setting the DTC
The ECM detects that the boost pressure sensor signal voltage is more than 4.95 volts.
Action Taken When the DTC Sets
| • | The ECM illuminates the malfunction indicator lamp (MIL) and Reduced Engine Power indicator lamp, if fitted, when the diagnostic runs and fails. |
| • | The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Failure Records. |
| • | The ECM uses boost pressure 100 kPa. |
| • | The ECM limits the fuel injection quantity for fail-safe operation. |
| • | The ECM limits fuel rail pressure for fail-safe operation. |
| • | The ECM inhibits cruise control. |
Condition for Clearing the DTC
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | Clear the malfunction indicator lamp (MIL) and the DTC with a scan tool. |
Diagnostic Aids
| • | If an intermittent condition is suspected, the following may cause an intermittent: |
| - | Poor connections |
| - | A misrouted harness |
| - | Rubbed through wire insulation |
| - | Broken wire inside the insulation |
| • | Inspect for the following conditions: |
| - | Poor connection at ECM--Inspect the harness connectors for the following conditions: |
| • | Backed-out terminals |
| • | Improper mating |
| • | Broken locks |
| • | Improperly formed or damaged terminals |
| • | Poor terminal to wire connection |
| - | Damaged harness--Inspect the wiring harness for damage. If the harness appears to be OK, observe the Engine Coolant Temperature display on the scan tool while moving the connectors and the wiring harness related to the sensor. A change in the display will indicate the location of the fault. |
Step | Action | Values | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||
1 | Did you perform the Diagnostic System Check - Engine Controls? | -- | Go to Step 2 | |||||
2 |
Did the DTC fail this ignition? | -- | Go to Step 3 | Go to Diagnostic Aids | ||||
3 |
Is DTC P0641 also set? | -- | Go to DTC P0641 | Go to Step 4 | ||||
4 |
Is the Boost Pressure Sensor parameter more than the specified value? | 5 psi (34 kPa) | Go to Step 6 | Go to Step 5 | ||||
5 |
Is the DMM voltage more than the specified range? | 4.5-5.5 V | Go to Step 8 | Go to Step 7 | ||||
6 |
Important: The boost pressure sensor may be damaged if the circuit is shorted to a voltage source.
Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12 | ||||
7 |
Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 9 | ||||
8 |
Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 10 | ||||
9 |
Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12 | ||||
10 |
Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 11 | ||||
11 | Replace the boost pressure sensor. Did you complete the replacement? | -- | Go to Step 13 | -- | ||||
12 |
Important: The new ECM must be programmed. Replace the ECM. Refer to Engine Control Module Replacement/Restore Fuel Rate Data . Did you complete the replacement? | -- | Go to Step 13 | -- | ||||
13 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 14 | ||||
14 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||
