T8 / P1456 00
Read the instructions below then
start the fault diagnostic procedure.
Symptom: Fault indicator lamp (for further information see WIS Fault diagnosis, general)
EVAP System, Fuel Level Sesor Failure and Very Small Leak Detected
Fault symptom
Fault indicator lamp (for further information see WIS Fault diagnosis, general)
On-board diagnosis
Type of diagnosis:
| Once per driving cycle. Stopped when fault criteria are fulfilled or OK reported. |
Enable criteria:
| • | The diagnosis is performed by closing the shut-off valve and opening the evap canister purge valve while the tank pressure is being registered. The pressure should then drop. |
| • | Bleeder valve closed; pressure increase in Pa/s calculated. Pressure must not rise too much. |
| Diagnostics can be carried out under 4 different operating conditions: |
| • | After cold start while stationary. |
| • | After cold start while driving. |
| • | After warm start while stationary. |
| • | After warm start while driving. |
| NONE of the following DTCs must be detected: |
| Diagnostics uses different calibration data for various operating conditions. Several conditions can interrupt diagnostics. After starting from cold, diagnostics restarts immediately if the vehicle speed exceeds 0 km/h. After warm start, a speed of over 44 km/h is required for a specific period of time before diagnostics restart. |
| Normally, the diagnosis takes 5 minutes with the engine idling if the intake temperature is above +15°C. |
Fault criteria:
| Pressure increase during phase 2 has been calculated and compared with fuel level in the tank. The pressure increase indicates a small leak; a hole with a diameter of 0.5 - 1.0 mm. |
| A fuel level sensor fault has been detected at the same time, which makes the EVAP diagnosis unreliable. |
Dependent:
System reaction to a fault:
OK report:
| Diagnostics carried out without fault reported. |
Fault handling:
| (See section Fault handling III, "Other emission-related components and functions" for more information.) |
Checking the wiring harness
Move the wiring harness at several spots and in several directions to reveal intermittent breaks and short-circuits. Check switches, connectors and crimp connections for oxidation, retracted pins and pin clamping force.
Diagnostic help
Diagnosis regards:
| Faulty fuel level sensor. |
| Checking EVAP system integrity. |
| In case of a fault in the sensor, the diagnosis will take 40 litres as a substitute value. When the EVAP diagnosis result has normalised above the fuel level, a fault may result even though there is no leak. Diagnose the fuel level sensor first and then check the EVAP system. |
Functions in the diagnostic tool related to the fault:
| (See also description of readings/activations in diagnostic tool) |
