Inspect the vehicle's ECM using check mode. Intermittent problems are easier to detect with an intelligent tester when the ECM is in check mode. In check mode, the ECM uses 1 trip detection logic, which is more sensitive to malfunctions than normal mode (default), which uses 2 trip detection logic.
Clear the DTCs.
Switch the ECM from normal mode to check mode using an intelligent tester.
Perform a simulation test.
Check and wiggle the harness(es), connector(s) and terminal(s).