Characteristic curves and target values
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The tank-leak diagnosis is started under the following conditions:
- Engine off: engine management system in after-run (15 seconds delay)
- Cold start: coolant temperature less than ambient temperature plus 6.8 °C
- Duration of the current journey: greater than 10 minutes, total above 40 km/h
- Tank fill level: between 1/4 and 3/4
- Ambient temperature: between 1.5 and 38 °C
- Height above mean sea level: less than 2400 meters
- Filling of activated charcoal filter: less than limit value (virtually full)
- Battery voltage: between 10.9 and 14.5 Volts
The fill level of the activated carbon filter is determined in the preceding drive cycle.
The minor leak diagnosis is carried out after every drive cycle (after stopping the engine) after the start conditions have been met. The superfine leak diagnosis is carried out after every second time the start conditions have been met (after stopping the engine).
| Index | Explanation |
|---|---|
| 1 | Current consumption for leak diagnosis pump |
| 2 | Activation of changeover valve |
| 3 | Reference leak phase (0.5 mm) |
| 4 | System leak-tight |
| 5 | Superfine leak (0.5 mm to 1 mm) |
| 6 | Minor leak, greater than 1 mm |
| 7 | Check with fuel cap open, leakage greater than 1.5 mm |
| 8 | Activation time (maximum 600 s) |
Observe the following target values for the diagnosis module for tank leakages:
| Variable | Value |
|---|---|
| Leak diagnosis pump, operating pressure | approx. 30 hPa |
| Leak diagnosis pump current consumption at rated voltage | 15 to 40 mA |
| Leak diagnosis pump resistance | 118 Ω |
| Heating element current consumption | approx. 0.3 A |
| Heating element rated voltage | 14 V |
| Temperature range | -40 to 80 °C |