DTC E30 is an ECCS C/U Error signal

Most common result is failed relay.

No supplied power to the ECM for some predetermined amount of time.
ECM detects insufficient power supply.
ECM pin 119-wire 189-wire color Key off/ Key on! Running 0/ Battery volts
ECM pin '120 Key off! Key on/ Running 0/ Battery volts
ECM Pin 121-wire 190-- wire color White. Must have battery volts all times
Check ECM grounds. Always 0,0 volts.

EGI relay 2 is a related circuit / Failed relay can produce this code.

Start checking fuel pressure, At idle must be 28 kpa (use the diagnostics to read this. On the 2007-8 fuel system 34
kpa)
When accelerating what is the pressure dropping to. if it drops low you have a fuel lock stuck partially or a failed
regulator valve. Check fuel pressure at high rpms and apply back tilt into relief. What is the pressure now ? If below '19
kpa, then you are starving for fuel. Check for failing vaporizer or block fuel lock filter.

Check the balance line at the injector holder (vacuum, hose from vaporizer to injection holder intake elbow, If you smell
fuel, replace the vaporizer. If no fuel, check for liquid fuel to be in the vapor hose. If found, replace the vaporizer. If no
liquid fuel.

Check assist injector for a stuck or unseated plunger.

Check at the lower relay box specifically the ignition relay. The terminals of the harness have been known to be rotted
off in the debris packed around the base. The terminals inside the relay box were also rotted away. in some cases
replacing the box and relay has resolved issue.