Circuit Description
The engine control module (ECM) monitors fuel rail pressure (FRP) using the FRP sensor. If the sensor indicates a pressure less than the commanded rail pressure plus a possible transitional overshoot, the ECM will set DTC P0087 for FRP too low.
DTC Descriptor
This diagnostic supports the following DTC:
DTC P0087 Fuel Rail Pressure (FRP) Too Low
Conditions for Running the DTC
| • | DTCs P0192, P0193, P0642 or P0643 are not set. |
| • | The ignition is ON. |
Conditions for Setting the DTC
The actual FRP is less than 0.0 MPa at 0-400 RPM.
OR
The actual FRP is less than 22.5 MPa at more than 600 RPM.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records. |
| • | The ECM will limit fuel injection. |
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. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
| • | A restricted fuel supply line may cause DTCs P0087 and P1093 to set at the same time. When ambient temperatures are below 0°C (32°F), the fuel tank pickup screen may be iced over from water in the fuel tank. Refer to Fuel System Diagnosis . |
| • | If power enhancing devices have been attached to the FRP sensor circuits, this DTC may set and adversely effect the fuel system components. Refer to Fuel System Diagnosis - High Pressure Side . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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If the fuel temperature is high enough to set DTC P0168, the fuel may be thin enough to cause this DTC to set.
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The engine will not start if the fuel leak is large enough.
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This step tests for fuel leaks into the engine oil.
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This step tests for an inaccurate FRP sensor.
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This step tests for a restriction in the fuel system between the fuel injection pump and the fuel tank.
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This test tests to see if the fuel injection pump is able to supply maximum fuel pressure at idle. The fuel injection pump should be able to create 145-158 MPa at idle. In extreme ambient or fuel temperatures, the fuel injection pump may only be able to generate a pressure at the low end of this range.
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This step tests for a restriction in the fuel system between the fuel injection pump and the fuel tank that may only cause symptoms at higher engine speed and load conditions.
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This step tests to see if the FRP sensor wiring and ECM are functioning normally.
-
If the vacuum is still too high in the fuel supply system after replacing the fuel filter, there is a restriction in the fuel supply lines or sending unit in the fuel tank.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Engine Controls? | -- | Go to Step 2 | |
Is DTC P0168 or DTC P0090 also set? | -- | Go to Step 3 | ||
Attempt to start the engine. Does the engine start and idle? | -- | Go to Step 4 | ||
4 |
Did the DTC fail this ignition? | -- | Go to Step 5 | Go to Diagnostic Aids |
Is the Actual Fuel Rail Pressure Parameter within the specified range? | 1-1.8 MPa | Go to Step 6 | Go to Step 10 | |
Check the engine oil for fuel contamination. Refer to Fuel in Engine Oil in Engine Mechanical. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 7 | |
Does the vacuum measure less than the specified value through the entire RPM range? | 5 in | Go to Step 8 | Go to Step 11 | |
Is the Actual Fuel Rail Pressure parameter more than the specified value? | 145 MPa | Go to Step 9 | ||
|
Important: If the fuel temperature is near 121°C (250°F) during the duplication of the complaint, or in the Failure Records for this DTC, check for a restriction in the fuel cooler air flow or the fuel heater always ON. Refer to Fuel Heater Always On . Operate the vehicle within the conditions for which the customer complaint occurs. Does the vacuum measure less than the specified value through the entire operating range? | 12 in | Go to Diagnostic Aids | Go to Step 11 | |
Does the Actual Fuel Rail Pressure measure more than the specified value? | 175 MPa | Go to Step 15 | Go to Step 14 | |
11 | Replace the fuel filter. Refer to Fuel Filter Replacement . Did you compete the replacement? | -- | Go to Step 12 | -- |
Does the vacuum measure less than or equal to the specified value? | 5 in at idle or 12 in at high speed | Go to Step 17 | Go to Step 13 | |
13 | Repair the restriction in the fuel supply lines between the fuel tank and the fuel injection pump. Refer to Fuel System Diagnosis . Did you complete the repair? | -- | Go to Step 17 | -- |
14 | Test the FRP sensor signal circuit for a short to ground. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 16 |
15 | Replace the FRP sensor. Refer to Fuel Injection Fuel Rail Fuel Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 17 | -- |
16 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 17 | -- |
17 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 18 |
18 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
