Circuit Description
The fuel supply pump draws fuel from the fuel tank and pumps the high pressure fuel to the fuel rail. The quantity of the fuel discharged from the supply pump controls the pressure in the fuel rail. The suction control valve (SCV) in the fuel supply pump effects this control in accordance with the command received from the engine control module (ECM). The fuel pressure of the high pressure side is measured by the fuel rail pressure (FRP) sensor. If the ECM detects an excessively high FRP, this DTC will set.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P2921 Fuel Rail Pressure (FRP) Too High
Conditions for Running the DTC
| • | The ignition is ON. |
| • | The battery voltage is between 10-16 volts. |
| • | The engine is running. |
| • | DTC P0192, P0193 is not set. |
Conditions for Setting the DTC
The ECM detects that the fuel rail pressure is more than 230 MPa (33,350 psi) for 1 second.
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 limits fuel injection quantity for fail-safe operation. |
| • | The ECM limits fuel rail pressure for fail-safe operation. |
| • | The ECM closes the exhaust gas recirculation (EGR) valve and holds to close position. |
| • | The ECM inhibits the cruise 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 malfunction indicator lamp (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.
| • | A sticking suction control valve (SCV) may have allowed the fuel pressure become high enough to set this DTC. |
| • | 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 wide open throttle (WOT), accelerator pedal full travel. |
| • | A skewed fuel rail pressure (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. |
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 |
Is DTC P0088, P0091, P0092, P0192, P0193, P0201-P0206, P1087, P1088, P1263-P1266, P2011, P2012, or P2921 also set? | -- | Go to Step 3 | |
3 |
Does the Actual Fuel Rail Pressure ever exceed the specified value? | 230 MPa (33,350 psi) | Go to Step 4 | Go to Diagnostic Aids |
4 |
Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 5 |
5 |
Was a condition found? | -- | System OK | Go to Step 6 |
6 |
Is there a change in the engine noise? | -- | Go to Step 8 | Go to Step 7 |
7 | Replace the injector. Refer to Fuel Injector Replacement and Fuel Injector Flow Rate Programming . Did you complete the replacement? | -- | Go to Step 20 | -- |
8 |
Did the DTC fail this ignition? | -- | Go to Step 9 | Go to Step 20 |
9 |
Is the fuel pressure value at the specified value? | 0 MPa | Go to Step 10 | Go to Step 12 |
10 |
Is the fuel pressure value within the specified range? | 25-40 MPa | Go to Step 13 | Go to Step 11 |
11 |
Was a condition found? | -- | Go to Step 15 | Go to Step 12 |
12 | Inspect the fuel rail pressure (FRP) sensor. Was a condition found? | -- | Go to Step 15 | Go to Step 19 |
13 |
Did the DTC fail this ignition? | -- | Go to Step 14 | Go to Step 20 |
14 |
Did the actual fuel rail pressure follow closely to desired fuel rail pressure through the entire operating range? | -- | Go to Step 15 | Go to Step 16 |
15 | Replace the fuel rail assembly. Did you complete the replacement? | -- | Go to Step 20 | -- |
16 |
Did the DTC fail this ignition? | -- | Go to Step 17 | Go to Step 20 |
17 | Replace the supply pump. Refer to Fuel Injection Pump Replacement . Did you complete the replacement? | -- | Go to Step 18 | -- |
18 |
Did the DTC fail this ignition? | -- | Go to Step 19 | Go to Step 20 |
19 |
Important: The new engine control module (ECM) must be programmed. Replace the ECM. Refer to Engine Control Module Programming and Setup , Engine Control Module Replacement/Restore Fuel Rate Data , and Fuel Injector Flow Rate Programming . 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 | |
