DTC P1088 Without RPO CTF
Circuit Description
The common rail is installed to the intake manifold. The common rail is equipped with a flow damper, a pressure limiter, and a common rail pressure (PC) sensor.
The common rail pressure sensor is installed at left end of the common rail. The sensor serves the detect fuel pressure.
The engine control module (ECM) monitors the common rail pressure signals for voltage outside the normal range of the common rail pressure sensor. If the ECM detects a common rail pressure signal voltage that is excessively high, DTC P1088 will be set.
Conditions for Running
DTC P0192 or P0193 are not set.
Conditions for Setting the DTC
| • | Common rail pressure 1st stage--common rail pressure over 160 MPa (23,205 psi) for 0.2 second |
| • | Common rail pressure 2nd stage--common rail pressure over 180 MPa (26,106 psi) for 0.2 second |
Action Taken When the DTC Sets
| • | The control module will not illuminate the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
| • | The ECM limits fuel delivery in stage 1. The ECM stops fuel delivery in stage 2. |
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 the harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connection. |
| • | A 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 display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display will indicate the location of the fault. |
Step | Action | Value | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||
1 | Is the DTC set? | -- | Go to Step 2 | Go to Intermittent Conditions | ||||
2 |
Does the voltage measure more than the specified value? | 4.2 V at 160 MPa (23,205 psi) | Go to Step 5 | Go to Step 3 | ||||
3 |
Important: To start the engine, disconnect PC sensor connector.
Does DTC P0088 or P1088 set? | -- | Go to Step 4 | Go to Step 7 | ||||
4 | Does the PC sensor voltage measure more than the specified voltage with the ignition ON? | 3 V | Go to Step 8 | Go to Step 3 | ||||
5 |
Does each resistance measure less than the specified value? | 0.5 ohms | Go to Step 6 | Go to Step 9 | ||||
6 | Measure resistance between pin number C4-8 and C4-19 at the ECM harness connector and a good ground. Does the resistance measure more than the specified value? | 10 M ohms | Go to Step 8 | Go to Step 10 | ||||
7 | Repair the poor connection at the connector. Did you complete the repair? | -- | Go to Step 13 | -- | ||||
8 | Replace the PC sensor. Did you complete the replacement? | -- | Go to Step 11 | -- | ||||
9 | Repair/replace the PC sensor wiring harness. Did you complete the action? | -- | Go to Step 13 | -- | ||||
10 | Replace the PC sensor wiring harness. Did you complete the replacement? | -- | Go to Step 11 | -- | ||||
11 | Reconnect all connectors. Does the DTC reset? | -- | Go to Step 12 | Go to Step 14 | ||||
12 | Replace the ECM. Did you complete the replacement? | -- | Go to Step 13 | -- | ||||
13 | Clear the DTCs. Does the DTC reset? | -- | Go to Step 2 | Go to Step 14 | ||||
14 | Do any other DTCs set? | -- | System OK | |||||
DTC P1088 With RPO CTF
Circuit Description
The engine control module (ECM) monitors fuel rail pressure (FRP) using the FRP sensor. If the sensor indicates a pressure more than the commanded rail pressure plus a possible transitional overshoot, the ECM will set DTC P088 for FRP too high.
Conditions for Running the DTC
| • | The ignition is ON. |
| • | The battery voltage is between 10-16 volts. |
Conditions for Setting the DTC
Fuel rail pressure is more than 33900 psi (234 mPa) anytime during the ignition cycle. This indicates the fuel pressure is too high and pressure limiter most likely did not activate.
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 part pressure for fail-safe operator. |
| • | The ECM closes the exhaust gas recirculation (EGR) valve and stops EGR control. |
| • | 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 MIL and the DTC with a scan tool. |
Diagnostic Aids
If an intermittent condition is suspected, the following may cause an intermittent:
| • | Poor connections |
| • | Misrouted harness |
| • | Rubbed through wire insulation |
| • | Broken wire inside the insulation |
Inspect for the following conditions:
| • | Poor connection at 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. If the harness appears to be OK, observe the DTC P1088 display on the scan tool while moving connectors and wiring harness related to the sensor. A change in the display will indicate the location of the fault. |
NOTE: The Actual Fuel Rail Pressure on 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 longer than 10 seconds.
| • | An intermittently sticking suction control valve (SCV) may have allowed the fuel pressure to become high enough to open the pressure limiter valve. |
| • | Normal Actual Fuel Rail Pressure readings on the scan with the engine running in Park or Neutral at idle are around 3650-5050 psi (20-35 mPa) and around 8700-18850 psi (60-130 mPa) in Park or Neutral at W.O.T. (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 psi (0 mPa) with the key ON and engine OFF after the engine has stopped 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 - Engine Controls? | -- | Go to Step 2 | |||||
2 |
Does the DTC fail this ignition? | -- | Go to Step 3 | Go to Diagnostic Aids | ||||
3 | Review the DTC.
Is DTC detected? | -- | Go to Step 4 | System OK | ||||
4 |
Was a problem found? | -- | System OK | Go to Step 5 | ||||
5 |
Was a problem found? | -- | System OK | Go to Step 6 | ||||
6 | Inspect the fuel pipe.
Was a problem found? | -- | System OK | Go to Step 7 | ||||
7 | Inspect the fuel injection state of a injector.
Change the engine noise? | -- | Go to Step 8 | Go to Step 9 | ||||
8 | Replace the injector. Refer to Fuel Injector Replacement . Is the action complete? | -- | Go to Step 20 | -- | ||||
9 |
Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 10 | ||||
10 | Using the scan tool, check the fuel pressure.
Is the fuel pressure value within the specified range? | 0 mPa | Go to Step 11 | Go to Step 13 | ||||
11 | Using the scan tool, check the fuel pressure.
Is the fuel pressure value within the specified range? | 25-40 mPa | Go to Step 12 | Go to Step 13 | ||||
12 | Check the fuel pressure in fuel rail.
Was a problem found? | -- | Go to Step 13 | Go to Step 11 | ||||
13 | Check the fuel rail pressure sensor. Was a problem found? | -- | Go to Step 17 | Go to Step 14 | ||||
14 |
Was a problem found? | -- | Go to Step 15 | Go to Step 16 | ||||
15 | Check the fuel pipe.
Was a problem found? | -- | Go to Step 20 | Go to Step 16 | ||||
16 | Recheck the fuel pressure in fuel rail.
Was a problem found? | -- | Go to Step 18 | Go to Step 17 | ||||
17 | Replace the fuel rail system assembly. Is the action complete? | -- | Go to Step 20 | -- | ||||
18 | Review the DTC.
Is DTC detected? | -- | Go to Step 19 | Go to Step 20 | ||||
19 |
Important: The replacement 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 stored information. Capture Info with a scan tool. Are there any DTCs that you have not diagnosed? | -- | System OK | |||||
