Fault-Tracing Information
Fault-tracing
Checking the fuel injection system
Note! If the diagnostic trouble code is generated, it is an indication that the fuel pressure has exceeded 800 kPa, there is a risk of fuel leakage. Therefore, it may be good to perform a check of the fuel system.
- Start the engine. Allow the engine to idle.
Check the fuel system for leaks.
Remedy as necessary.
Continue - Checking the fuel pressure sensor
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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 comparing the fuel pressure sensor signal (displayed in VIDA) with the actual fuel pressure (displayed on a manometer connected to the wiring for the fuel injection system).
- Connect the pressure gauge: Fuel pressure gauge Fuel Pressure Gauge
Caution! The pressure in the fuel injection system can reach approx. 800 kPa when this diagnostic trouble code is stored, use an adapted 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 roughly the same. If the values are different, the circuit for the fuel pressure sensor is defective.
Is the fuel pressure sensor correct?
Yes - Checking components
No - Checking the component and wiring
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Checking components
Check the connectors between fuel pump module and the fuel pump for contact resistance and oxidation.
Remedy as necessary.
Try a new fuel pump (FP) control module if no fault is found during the above fault-tracing.
Other information
- Fuel pump driver module, B5254T7 Service and Repair
- Checking wiring and terminals Checking Wiring and Terminals
Continue - Verification
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Checking the component 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
- Checking wiring and terminals Checking Wiring and Terminals
Continue - Verification
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Verification
Verification
Hint: After carrying out the repair, check that the fault has been remedied.
- Connect a 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 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
Hint: After carrying out the repair, check that the fault has been remedied.
- Run the engine to operating temperature. Allow the engine to idle.
- air conditioning (A/C) off
- Read off the fuel pressure and the fuel pressure desired value.
- Start the quick test when the engine is running at idling.
During the course of the quick test, the control module regulates the pressure for different target values in different steps (530, 490, 450, 410, 440, 490, 530 kPa). Each step takes 10 seconds. The test usually starts with the pressure momentarily going up to 650 kPa.
Note! Because the by-pass valve in the fuel pump (FP) will be open at approximately 650 kPa, the pressure will not go higher than this.
Hint: The illustration to the left shows an example of normal regulation.
- The upper digital display and the graphic display (red font color) indicate the absolute fuel pressure, calculated from the fuel pressure sensor
- The central digital display and the graphic display (blue font color) indicate the control module target value for the absolute fuel pressure
- 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 must indicate this pressure.
Check that the value for absolute fuel pressure is the same as the target value for absolute fuel pressure. If the values are not the same, this indicates a fault in the pressure regulation. The values may differ during the quick test when the target value is changed. This is due to sluggishness in the fuel regulation and is normal. In some cases, it can take up to 5 seconds before the fuel pressure reaches the target value for the fuel pressure.
Is the function OK?
Yes - VERIFIED
No - VERIFICATION FAILED
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VERIFICATION FAILED - Fault-tracing information
VERIFIED - FAULT FOUND
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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 - Exit fault-tracing
No - Attempt New Test
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FAULT-TRACING FAILED - No Fault Found
Attempt New Test - Checking the fuel injection system
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