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 fuel rail pressure too low.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0087 Fuel Rail Pressure (FRP) Too Low
Conditions for Running the DTC
| • | The battery voltage is between 10-16 volts. |
| • | The ignition is ON. |
| • | The engine speed is more than 500 RPM. |
| • | DTC P0091, P0092, P0192, P0193, P0201-P0206, P0335, P1087, P1088, P1263-P1266, P2011, or P2012 are not set. |
Conditions for Setting the DTC
The fuel injection volume does not follow the target fuel injection volume.
OR
The fuel rail pressure does not follow the target fuel rail pressure.
Action Taken When the DTC Sets
| • | The ECM illuminates the malfunction indicator lamp (MIL) and reduced engine power indicator lamp, if equipped, 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 limits the accelerator operating range. |
| • | The ECM limits the fuel injection quantity. |
| • | The ECM limits the fuel rail pressure. |
| • | The ECM closes the exhaust gas recirculation (EGR) valve and stops EGR control. |
| • | The ECM inhibits cruise control. |
| • | The ECM inhibits power take-off (PTO) control. |
Conditions for Clearing the DTC
| • | The MIL resets when the ignition is turned OFF. |
| • | 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
Important: The Actual Fuel Rail Pressure on the scan tool will only update with the engine running or one time after the key is cycled when the ignition has been turned OFF for more than 10 seconds.
| • | An intermittently sticking suction control valve (SCV) may have allowed the fuel pressure to drop suddenly. |
| • | Normal actual fuel rail pressure readings on the scan with the engine running Park or Neutral at idle are 25-35 MPa (3,650-5,050 psi) and 60-130 MPa (8,700-18,850 psi) in Park or Neutral at WOT, accelerator pedal full travel. |
| • | An intermittently sticking fuel injector may have allowed the fuel pressure to drop too much. Use a scan tool to perform the Cylinder Power Balance Test for each injector. Verify a consistent engine speed change when commanding each fuel injector ON and OFF. |
| • | A skewed FRP sensor value, shifted to a higher pressure, can set this DTC. The actual fuel rail pressure on the scan tool should read 0 MPa (0 psi) with the key ON and the engine OFF after the engine has stopped running for a minimum of 2 minutes. |
| • | Resistance in the FRP sensor low reference circuit can set this DTC. Ensure that the sensor low reference circuit has no resistance and the connectors are tight and free of corrosion. |
| • | The fuel system from the fuel tank to the fuel supply pump is under a slight vacuum with the engine running. As a result, air can enter the fuel system if these connections are not tight or if there is a crack in one of the fuel hoses. Air in the fuel system will cause fuel rail pressure fluctuations especially at high engine speed and load, which may set this DTC. |
Step | Action | Values | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||
2 |
Did the DTC fail this ignition? | -- | Go to Step 3 | Go to Intermittent Conditions | ||||
3 |
Did the DTC fail this ignition? | -- | Go to Step 4 | System OK | ||||
4 |
Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 5 | ||||
5 |
Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 6 | ||||
6 | Inspect the fuel pipe.
Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 7 | ||||
7 |
Is there a change in the engine noise? | -- | Go to Step 9 | Go to Step 8 | ||||
8 | Replace the fuel injector. Refer to Fuel Injector Replacement and Fuel Injector Flow Rate Programming . Did you complete the replacement? | -- | Go to Step 20 | -- | ||||
9 |
Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 10 | ||||
10 |
Is the parameter near the specified value? | 0 MPa | Go to Step 11 | Go to Step 13 | ||||
11 |
Is the parameter within the specified range? | 25-40 MPa (3,626-5,801 psi) | Go to Step 13 | Go to Step 12 | ||||
12 |
Was a condition found? | -- | Go to Step 13 | Go to Step 11 | ||||
13 | Inspect the fuel rail pressure sensor. Was a condition found? | -- | Go to Step 17 | Go to Step 14 | ||||
14 |
Was a condition found? | -- | Go to Step 15 | Go to Step 16 | ||||
15 |
Was a condition found? | -- | Go to Step 20 | Go to Step 16 | ||||
16 |
Did the actual fuel rail pressure follow closely to desired fuel rail pressure through the entire operating range? | -- | Go to Step 17 | Go to Step 18 | ||||
17 | Replace the fuel rail system assembly. Did you complete the replacement? | -- | Go to Step 20 | -- | ||||
18 |
Did the DTC fail this ignition? | -- | Go to Step 19 | Go to Step 20 | ||||
19 |
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 20 | -- | ||||
20 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 21 | ||||
21 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||
