A method for testing an ignition device associated with a cylinder of an internal combustion engine , the ignition device being configured to supply a pilot injection of liquid fuel to the cylinder to cause an ignition of a mixture of gaseous fuel and air in a combustion chamber of the cylinder , the method comprising: operating the internal combustion engine with a first pilot injection timing (ti) of the ignition device , the injection timing being the timing of the start of injection of the pilot fuel by the ignition device ; retarding the pilot injection timing to operate the internal combustion engine with a second pilot injection timing (t 2 ) of the ignition device that is later than the first pilot injection timing; measuring at least one combustion parameter while operating with the second pilot injection timing, the at least one combustion parameter being obtained based on measurements performed with a cylinder pressure sensor system provided for the engine and being at least one of: a start of combustion in the cylinder , a peak firing pressure in the cylinder , a duration of combustion and a cylinder pressure measured at a predetermined timing before or after a main injection timing; advancing the pilot injection timing to operate the internal combustion engine with a third pilot injection timing (t 3 ) of the ignition device that is earlier than the first pilot injection timing; measuring the at least one combustion parameter while operating with the third pilot injection timing; comparing the measurement of the at least one combustion parameter for the second pilot injection timing (t 2 ) with the measurement of the at least one combustion parameter for the third pilot injection timing (t 3 ); and determining whether the ignition device is functional based on the comparison. operating the internal combustion engine with a first pilot injection timing (ti) of the ignition device , the injection timing being the timing of the start of injection of the pilot fuel by the ignition device ; retarding the pilot injection timing to operate the internal combustion engine with a second pilot injection timing (t 2 ) of the ignition device that is later than the first pilot injection timing; measuring at least one combustion parameter while operating with the second pilot injection timing, the at least one combustion parameter being obtained based on measurements performed with a cylinder pressure sensor system provided for the engine and being at least one of: a start of combustion in the cylinder , a peak firing pressure in the cylinder , a duration of combustion and a cylinder pressure measured at a predetermined timing before or after a main injection timing; advancing the pilot injection timing to operate the internal combustion engine with a third pilot injection timing (t 3 ) of the ignition device that is earlier than the first pilot injection timing; measuring the at least one combustion parameter while operating with the third pilot injection timing; comparing the measurement of the at least one combustion parameter for the second pilot injection timing (t 2 ) with the measurement of the at least one combustion parameter for the third pilot injection timing (t 3 ); and determining whether the ignition device is functional based on the comparison. <EOS>