Engine Performance Diagnostic Trouble Code (DTC) Diagnostics - 8 of 14 (Convertible): Overview Volvo C70 I

General information about testing the fuel tank system

The engine management system has a built-in function for carrying out a quick check of fuel tank system sealing. By activating the function, the control module determines faster than usual whether the fuel tank system is fault free or if there is any leakage. The conditions for this test are that

1. Engine idling
2. The engine coolant temperature (ECT) is higher than 70 °C
3. There is not too much fuel in the tank
4. Fuel evaporation is not too high during the leakage test (increased evaporation gives a pressure increase in the tank system).

The amount of vaporization permitted varies depending on the leakage test. Higher vaporization is permitted for the 1.0 mm than the 0.5 mm leakage test. If the test for 1.0 mm leaks starts but not for 0.5 mm leaks ("Smallest leak"), it may be because the fuel vaporization is too high.

HINT: There is high vaporization in warm conditions. Vaporization increases also if winter fuel is used in warm conditions. Fuel vaporization can be decreased by allowing the fuel to cool. If there is difficulty spray water on the fuel tank to speed up the fuel cooling down.

For further information about the fuel tank system diagnostic, see Leak diagnostic.

1. Canister purge (CP) valve
2. EVAP canister
3. EVAP canister shut-off valve
4. Fuel tank pressure sensor
5. Air cleaner (ACL).

Scheme 365

1. Continue Refer to «Checking the engine coolant temperature (ECT)»(ref-404045-S12879691912011061000000)

The engine control module (ECM) has a built-in function to quickly check the tank system for leaks. Upon function activation, the control module determines whether the tank system and all of its components and hoses are fault-free or have leaks. Conditions for the test are

1. Engine speed < 3500 RPM.
2. Engine temperature 30 °C.
3. Normal battery voltage.
4. Quantity of fuel in the tank < 60 liters.
5. Height above sea level < 2500 m.
6. Fuel evaporation is not too high (increased fuel evaporation increases pressure in the tank system).

The amount of fuel evaporation permitted varies depending on the leakage test. Higher fuel evaporation is permitted at 1.0 mm leakage test as compared to 0.5 mm leakage test.

HINT: Evaporation increases under warm conditions. It increases even more when winter fuel is used under warm conditions. Fuel evaporation can be reduced by allowing the fuel to cool. Speed cooling by spraying the fuel tank with cold water.

Other information

1. For more information on tank system diagnostics: «Leak diagnostics»(ref-404046-S07984878512011061000000)

1. Canister purge (CP) valve
2. EVAP canister
3. EVAP canister shut-off valve
4. Fuel tank pressure sensor
5. Air cleaner (ACL)

1. Continue Refer to «Starting the quick test»(ref-404045-S29436014902011061000000)

See also:
• Signal specification
• Safety regulations for handling fuel
• 9995646