1.4.1.2 Very Small Leak Check
P0456 (DMTKmax)
The very small leak check is performed if and only if the small leak check has been performed and no small leak was detected.
If the enable conditions for the very small leak check (> 0.02 in) are fulfilled, the pump's motor remains in the active state (monitoring mode) until its current exceeds the reference current, or the motor current gradient is close to zero (current stabilizes below the reference current). If the motor current exceeds the reference current, the evaporative system is considered as tight. A very small leak is assumed only if a second very small leak check confirms a current stabilization below the reference current.
If the motor's current decreases during one of the checks, the check is aborted. If the number of subsequent unsteady current events exceeds a calibrated value the fault code "module error" is set.
Figure 16 shows typical pump motor current characteristics: