P1026

P1026

Diagnosis information - Control unit DME (DFI)

Fuel high pressure implausible

Information:
- Faults in the fuel high-pressure injection system are often caused by defects in the pre-delivery system (fuel low pressure).
- Therefore, if there are problems in the fuel high-pressure injection area, the predelivery circuit must be checked first.
- The fault type [Upper limit value exceeded] or [Lower limit value not reached] does not necessarily have any significance.
- It is possible to read out in the extended fault memory whether the fault entry has been caused by the value exceeding or not reaching the respective limit:

- refer to the fault memory under
--> [F8]
--> [[F5] ENVIRONMENTAL CONDITIONS]
--> [Environmental conditions when fault first occurred]
--> Environment 6 (last value) is the fuel high pressure when the fault occurred:
- Value < 10 bar means that the pressure was below the limit
- Value > 135 bar means that the limit was exceeded

- Conversion:
- 10,000 hPa = 10 bar = 10,000 mbar
- 1,000 kPa = 10 bar = 10,000 mbar
- 1 MPa = 10 bar = 10,000 mbar

Diagnostic conditions
- Battery positive voltage > 9 V
- Engine start recognized > 5 sec.
- Engine temperature - 10 °C ...+ 100 °C (14 °F ... 212 °F)
- Engine running (driving)

Fault setting conditions
- Continuous average fuel high pressure < 10 bar
or
- Continuous average fuel high pressure > 135 bar

Possible fault causes
- Only if the value is below the lower limit:
- Predelivery quantity or pressure in fuel low-pressure circuit too low
- Tank (almost) (driven) empty
- refer to the fault memory under
--> [F8]
--> [[F8] EXTENDED FAULT MEMORY]
--> Value [Fuel Level Input]
--> The value is then [0%]

- If the value is below or exceeds the limits:
- Quantity control valve faulty (in fuel high-pressure pump)
- Fuel high-pressure pump faulty