Faulty Signal
Faulty signal
Checking the fuel pressure sensor
Note! If diagnostic trouble codes (DTC) for the fuel pressure sensor or atmospheric pressure sensor are stored, these diagnostic trouble codes (DTC) must be fault-traced and remedied first.
Hint: The method below is used to check whether the diagnostic trouble code (DTC) was caused by a faulty fuel pressure sensor. This can be done by checking whether the fuel pressure sensor signal (displayed in VIDA) is unstable, while the actual fuel pressure (displayed on a manometer connected to the wiring for the fuel injection system) is stable.
- Connect the manometer. See Fuel pressure gauge Fuel Pressure Gauge
Caution! The pressure in the fuel injection system can reach approximately 650 kPa when this diagnostic trouble code (DTC) is stored. Use an adapted manometer.
- Run the engine to operating temperature. Allow the engine to idle
- Air conditioning (A/C) off.
Read off the relative fuel pressure.
The relative fuel pressure is calculated using the signals from the fuel pressure sensor and the atmospheric pressure sensor (= absolute pressure minus atmospheric pressure).
Check the value on the manometer and the value displayed in VIDA. If the fuel pressure sensor signal (displayed in VIDA) is unstable while the actual fuel pressure (displayed on the manometer connected to the wiring for the fuel injection system) is stable, this indicates that the circuit for the fuel pressure sensor is defective.
Is the fuel pressure sensor correct?
Yes - Checking components
No - Checking components and wiring
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Checking components
Check that the fuel level in the tank is not too low (almost no fuel).
Check the connectors between the fuel pump (FP) control module and the fuel pump (FP). Check for contact resistance. Check for oxidation.
Check the fuel lines and fuel filter for blockage and leaks.
Remedy as necessary.
Try a new fuel pump (FP) if no fault is found during the above fault-tracing.
Hint: The diagnostic trouble code (DTC) can also be caused by a defective fuel pump (FP) control module.
Other information
- Level sensor, fuel tank/fuel pump, replacement Level Sensor, Fuel Tank/Fuel Pump, Replacement
- Control module fuel pump (FP), replacing, B5244T5, B5254T2 Service and Repair
- Checking wiring and terminals Checking Wiring And Terminals
Continue - Verification
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Checking components and wiring
Check the fuel pressure sensor connectors. Check for contact resistance and oxidation.
Remedy as necessary.
Try a new fuel pressure sensor if no fault is found during the above fault-tracing.
Other information
- Connecting the breakout box Connecting the Breakout Box
- Signal specification Signal Description / Specification
- Fuel pressure sensor Service and Repair
- Checking wiring and terminals Checking Wiring And Terminals
Continue - Verification
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Verification
Verification
Verification
Hint: After carrying out the repair, check that the fault has been remedied.
Caution! The pressure in the fuel injection system can reach approximately 650 kPa when this diagnostic trouble code (DTC) is stored. Use an adapted manometer.
- Connect the manometer. See Fuel pressure gauge Fuel Pressure Gauge
- Run the engine to operating temperature. Allow the engine to idle
- Air conditioning (A/C) off.
Read off the relative fuel pressure.
The relative fuel pressure is calculated from the fuel pressure sensor and the atmospheric pressure sensor signal (= absolute pressure minus atmospheric pressure).
Check that the value on the manometer and the value displayed in VIDA are the same. If the values are different, this indicates incorrect function.
Is the function OK?
Yes - VERIFIED
No - VERIFICATION FAILED
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VERIFIED - Fault Found
VERIFICATION FAILED - Fault-tracing information
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Verification
Verification
Verification
Hint: After carrying out the repair, check that the fault has been remedied.
- Ignition off
- Reinstall the connectors, components etc.
- Engine idling
- Read off the fuel pressure and the fuel pump (FP) work load.
- The upper digital display and the graphic display (red font color) indicate the absolute fuel pressure, calculated from the fuel pressure sensor
- The center digital display (blue font color) indicates the current work load required for the fuel pump (FP) to maintain the present fuel pressure. (Normal value 50 % ±10 %.)
- The lower digital display indicates the relative fuel pressure (white font color), calculated from the fuel pressure sensor and the atmospheric pressure sensor (= absolute pressure minus atmospheric pressure). If a manometer is connected during the test, it should indicate this pressure.
Check the fuel pressure value together with the value for the fuel pump (FP) work load. The requested pressure is 380 kPa at idling speed. A (relative) fuel pressure lower than 380 kPa together with a high fuel pump (FP) work load indicates a fault in pressure regulation.
Is the signal within its permitted range?
Yes - VERIFIED
No - VERIFICATION FAILED
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VERIFIED - Fault Found
VERIFICATION FAILED - Fault-tracing information
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Fault-tracing information
Information
Fault-tracing information
The fault should have been detected and remedied. As this is not the case fault-tracing has failed.
Exit fault-tracing for this diagnostic trouble code (DTC) or make another attempt.
Do you want to exit fault-tracing?
Yes - FAULT-TRACING FAILED
No - Attempt New Test
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Attempt New Test - Checking the fuel pressure sensor
FAULT-TRACING FAILED - No Fault Found
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